The thread at http://thread.gmane.org/gmane.comp.version-control.git/257392
details problems when applying patches with "git am" in a repository with
CRLF line endings. In the example in the thread, the repository originated
from "git-svn" so it is not possible to use core.eol and friends on it.
Right now, the best option is to use "git am --keep-cr". However, when
a patch create new files, the patch application process will reject the
new file because it finds a "/dev/null\r" string instead of "/dev/null".
The problem is that SMTP transport is CRLF-unsafe. Sending a patch by
email is the same as passing it through "dos2unix | unix2dos". The newly
introduced CRLFs are normally transparent because git-am strips them. The
keepcr=true setting preserves them, but it is mostly working by chance
and it would be very problematic to have a "git am" workflow in a
repository with mixed LF and CRLF line endings.
The MIME solution to this is the quoted-printable transfer enconding.
This is not something that we want to enable by default, since it makes
received emails horrible to look at. However, it is a very good match
for projects that store CRLF line endings in the repository.
The only disadvantage of quoted-printable is that quoted-printable
patches fail to apply if the maintainer uses "git am --keep-cr". This
is because the decoded patch will have two carriage returns at the end
of the line. Therefore, add support for base64 transfer encoding too,
which makes received emails downright impossible to look at outside
a MUA, but really just works.
The patch covers all bases, including users that still live in the late
80s, by also providing a 7bit content transfer encoding that refuses
to send emails with non-ASCII character in them. And finally, "8bit"
will add a Content-Transfer-Encoding header but otherwise do nothing.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
After the next patch, git-send-email will sometimes modify
existing Content-Transfer-Encoding headers. Delay the addition
of the header to @xh until just before sending. Do the same
for MIME-Version, to avoid adding it twice.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
* mt/send-email-cover-to-cc:
t9001: avoid non-portable '\n' with sed
test/send-email: to-cover, cc-cover tests
git-send-email: two new options: to-cover, cc-cover
Allow extracting To/Cc addresses from the first patch
(typically the cover letter), and use them as To/Cc addresses of the
remainder of the series.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Tighten the regexp used in the "file_name_is_absolute" replacement
used on msys to declare that only "[a-zA-Z]:" that appear at the
very beginning is a path with a drive-prefix.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
On Windows, absolute paths might start with a DOS drive prefix,
which these two checks failed to recognize.
Unfortunately, we cannot simply use the file_name_is_absolute
helper in File::Spec::Functions, because Git for Windows has an
MSYS-based Perl, where this helper doesn't grok DOS
drive-prefixes.
So let's manually check for these in that case, and fall back to
the File::Spec-helper on other platforms (e.g Win32 with native
Perl)
Signed-off-by: Erik Faye-Lund <kusmabite@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The "if /etc/ssl/certs/ directory exists, explicitly telling the
library to use it as SSL_ca_path" blind-defaulting in "git
send-email" broke platforms where /etc/ssl/certs/ directory exists,
but it cannot used as SSL_ca_path (e.g. Fedora rawhide). Fix it by
not specifying any SSL_ca_path/SSL_ca_file but still asking for peer
verification in such a case.
* rk/send-email-ssl-cert:
send-email: /etc/ssl/certs/ directory may not be usable as ca_path
When sending patches on Fedora rawhide with
git-1.8.5.2-1.fc21.x86_64 and perl-IO-Socket-SSL-1.962-1.fc21.noarch,
with the following
[sendemail]
smtpencryption = tls
smtpserver = smtp.gmail.com
smtpuser = ruben@rubenkerkhof.com
smtpserverport = 587
git-send-email fails with:
STARTTLS failed! SSL connect attempt failed with unknown error
error:14090086:SSL routines:SSL3_GET_SERVER_CERTIFICATE:certificate
verify failed at /usr/libexec/git-core/git-send-email line 1236.
The current code detects the presence of /etc/ssl/certs directory
(it actually is a symlink to another directory, but that does not
matter) and uses SSL_ca_path to point at it when initializing the
connection with IO::Socket::SSL or Net::SMTP::SSL. However, on the
said platform, it seems that this directory is not designed to be
used as SSL_ca_path. Using a single file inside that directory
(cert.pem, which is a Mozilla CA bundle) with SSL_ca_file does work,
and also not specifying any SSL_ca_file/SSL_ca_path (and letting the
library use its own default) and asking for peer verification does
work.
By removing the code that blindly defaults $smtp_ssl_cert_path to
"/etc/ssl/certs", we can prevent the codepath that treats any
directory specified with that variable as usable for SSL_ca_path
from incorrectly triggering.
This change could introduce a regression for people on a platform
whose certificate directory is /etc/ssl/certs but its IO::Socket:SSL
somehow fails to use it as SSL_ca_path without being told. Using
/etc/ssl/certs directory as SSL_ca_path by default like the current
code does would have been hiding such a broken installation without
its user needing to do anything. These users can still work around
such a platform bug by setting the configuration variable explicitly
to point at /etc/ssl/certs.
This change should not negate what 35035bbf (send-email: be explicit
with SSL certificate verification, 2013-07-18), which was the
original change that introduced the defaulting to /etc/ssl/certs/,
attempted to do, which is to make sure we do not communicate over
insecure connection by default, triggering warning from the library.
Cf. https://bugzilla.redhat.com/show_bug.cgi?id=1043194
Tested-by: Igor Gnatenko <i.gnatenko.brain@gmail.com>
Signed-off-by: Ruben Kerkhof <ruben@rubenkerkhof.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When --smtp-encryption=ssl, we use a Net::SMTP::SSL connection,
passing its ->new all the options that would otherwise go to
Net::SMTP->new (most options) and IO::Socket::SSL->start_SSL (for the
SSL options).
However, while Net::SMTP::SSL replaces the underlying socket class
with an SSL socket, it does nothing to allow passing options to that
socket. So the SSL-relevant options are lost.
Fortunately there is an escape hatch: we can directly set the options
with IO::Socket::SSL::set_client_defaults. They will then persist
within the IO::Socket::SSL module.
Signed-off-by: Thomas Rast <tr@thomasrast.ch>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
35035bb (send-email: be explicit with SSL certificate verification,
2013-07-18) forgot to specify that --smtp-ssl-cert-path takes a string
argument. This means that the option could not actually be used as
intended. Presumably noone noticed because it's much easier to set it
through configs anyway.
Add the required "=s".
Signed-off-by: Thomas Rast <tr@thomasrast.ch>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We forgot to pass the Debug option through to Net::SMTP::SSL->new --
which is the same as Net::SMTP->new. This meant that with security
set to SSL, we would never enable debug output.
Pass through the flag.
Signed-off-by: Thomas Rast <tr@thomasrast.ch>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
If SSL verification is enabled in git send-email, we could attempt to call a
method on an undefined value if the verification failed, since $smtp would end
up being undef. Look up the error string in a way that will produce a helpful
error message and not cause further errors.
Signed-off-by: Brian M. Carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Newer Net::SMTP::SSL module does not want the user programs to use
the default behaviour to let server certificate go without
verification, so by default enable the verification with a
mechanism to turn it off if needed.
* rr/send-email-ssl-verify:
send-email: be explicit with SSL certificate verification
When initiating an SSL connection without explicitly specifying the
SSL certificate verification mode, Net::SMTP::SSL defaults to no
verification, but recent versions of the module gives a warning
against this use of the default.
Enable certificate verification by default, using /etc/ssl/certs as
the default path for certificates of certificate authorities. This
path can be overriden by the --smtp-ssl-cert-path command line
option and the sendemail.smtpSSLCertPath configuration variable.
Passing an empty string as the path for CA certificates path disables
the SSL certificate verification explicitly, which does not trigger
the warning from recent versions of Net::SMTP::SSL.
Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
Helped-by: Brian M. Carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Pass port number as a separate argument when send-email initializes
Net::SMTP, instead of as a part of the hostname, i.e. host:port.
This allows GSSAPI codepath to match with the hostname given.
* bc/send-email-use-port-as-separate-param:
send-email: provide port separately from hostname
If the SMTP port is provided as part of the hostname to Net::SMTP, it passes
the combined string to the SASL provider; this causes GSSAPI authentication to
fail since Kerberos does not want the port information. Instead, pass the port
as a separate argument as is done for SSL connections.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Logic used by git-send-email to suppress cc mishandled names that
need RFC2047 quoting.
* mt/send-email-cc-match-fix:
send-email: sanitize author when writing From line
send-email: add test for duplicate utf8 name
sender is now sanitized, but we didn't sanitize author when checking
whether From: line is needed in the message body.
As a result git started writing duplicate From: lines when author
matched sender and has utf8 characters.
Reported-by: SZEDER Gábor <szeder@ira.uka.de>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: SZEDER Gábor <szeder@ira.uka.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Logic git-send-email used to suppress cc mishandled names like "A
U. Thor" <author@example.xz>, where the human readable part needs
to be quoted (the user input may not have the double quotes around
the name, and comparison was done between quoted and unquoted
strings).
* mt/send-email-cc-match-fix:
test-send-email: test for pre-sanitized self name
t/send-email: test suppress-cc=self with non-ascii
t/send-email: add test with quoted sender
send-email: make --suppress-cc=self sanitize input
t/send-email: test suppress-cc=self on cccmd
send-email: fix suppress-cc=self on cccmd
t/send-email.sh: add test for suppress-cc=self
--suppress-cc=self fails to filter sender address in many cases where it
needs to be sanitized in some way, for example quoted:
"A U. Thor" <author@example.com>
To fix, make send-email sanitize both sender and the address it is
compared against.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When cccmd is used, old-style suppress-from filter
is applied by the newer suppress-cc=self isn't.
Fix this up.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Three years and a half is probably more than enough time to give users
the opportunity to configure Git to do what they want. If they haven't
changed the configuration by now, this warning message is not going to
do anything for them anyway.
This effectively reverts commit 528fb08 (prepare send-email for smoother
change of --chain-reply-to default).
Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Some people always do --annotate, lets not force them to always type
that.
Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Update "git send-email" for issues noticed by PerlCritic.
* rr/send-email-perl-critique:
send-email: use the three-arg form of open in recipients_cmd
send-email: drop misleading function prototype
send-email: use "return;" not "return undef;" on error codepaths
Perlcritic does not want to see the trailing pipe in the two-args
form of open(), i.e.
open my $fh, "$cmd \Q$file\E |";
If $cmd were a single-token command name, it would make a lot more
sense to use four-or-more-args form "open FILEHANDLE,MODE,CMD,ARGS"
to avoid shell from expanding metacharacters in $file, but we do
expect multi-word string in $to_cmd and $cc_cmd to be expanded by
the shell, so we cannot rewrite it to
open my $fh, "-|", $cmd, $file;
for extra safety. At least, by using this in the three-arg form:
open my $fh, "-|", "$cmd \Q$file\E";
we can silence Perlcritic, even though we do not gain much safety by
doing so.
Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The subroutine check_file_rev_conflict() is called from two places,
both of which expects to pass a single scalar variable and see if
that can be interpreted as a pathname or a revision name. It is
defined with a function prototype ($) to force a scalar context
while evaluating the arguments at the calling site but it does not
help the current calling sites. The only effect it has is to hurt
future calling sites that may want to build an argument list in an
array variable and call it as check_file_rev_confict(@args).
Drop the misleading prototype, as Perlcritic suggests.
While at it, rename the function to avoid new call sites unaware of
this change arising and add a comment clarifying what this function
is for.
Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
All the callers of "ask", "extract_valid_address", and "validate_patch"
subroutines assign the return values from them to a single scalar:
$var = subr(...);
and "return undef;" in these subroutine can safely be turned into a
simpler "return;". Doing so will also future-proof a new caller that
mistakenly does this:
@foo = ask(...);
if (@foo) { ... we got an answer ... } else { ... we did not ... }
Note that we leave "return undef;" in validate_address on purpose,
even though Perlcritic may complain. The primary "return" site of
the function returns whatever is in the scalar variable $address, so
it is pointless to change only the other "return undef;" to "return".
The caller must be prepared to see an array with a single undef as
the return value from this subroutine anyway.
Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
If smtp_user is provided but smtp_pass is not, instead of
prompting for password, make git-send-email use git
credential command instead.
Signed-off-by: Michal Nazarewicz <mina86@mina86.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When user spells "cc:" in lowercase in the fake "header" in the
trailer part, send-email failed to pick up the addresses from
there. As e-mail headers field names are case insensitive, this
script should follow suit and treat "cc:" and "Cc:" the same way.
* nz/send-email-headers-are-case-insensitive:
git-send-email: treat field names as case-insensitively
Field names like To:, Cc:, etc. are case-insensitive; use a
case-insensitive regexp to match them as such.
Previously, git-send-email would fail to pick-up the addresses when
in-body "fake" headers with different cases (e.g. lowercase "cc:")
are manually inserted to the messages it was asked to send, even
though the text will still show them.
Signed-off-by: Nickolai Zeldovich <nickolai@csail.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
* km/send-email-remove-cruft-in-address:
git-send-email: allow edit invalid email address
git-send-email: ask what to do with an invalid email address
git-send-email: remove invalid addresses earlier
git-send-email: fix fallback code in extract_valid_address()
git-send-email: remove garbage after email address
In some cases the user may want to send email with "Cc:" line with
email address we cannot extract. Now we allow user to extract
such email address for us.
Signed-off-by: Krzysztof Mazur <krzysiek@podlesie.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We used to warn about invalid emails and just drop them. Such warnings
can be unnoticed by user or noticed after sending email when we are not
giving the "final sanity check [Y/n]?"
Now we quit by default.
Signed-off-by: Krzysztof Mazur <krzysiek@podlesie.net>
Suggested-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Some addresses are passed twice to unique_email_list() and invalid addresses
may be reported twice per send_message. Now we warn about them earlier
and we also remove invalid addresses.
This also removes using of undefined values for string comparison
for invalid addresses in cc list processing.
Signed-off-by: Krzysztof Mazur <krzysiek@podlesie.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Currently we keep getting questions even when the user has properly
configured his full name and password:
Who should the emails appear to be from?
[Felipe Contreras <felipe.contreras@gmail.com>]
And once a question pops up, other questions are turned on. This is
annoying.
The reason it's safe to avoid this question is because currently the
script fails completely when the author (or committer) is not correct,
so we won't even be reaching this point in the code.
The scenarios, and the current situation:
1) No information at all, no fully qualified domain name
fatal: empty ident name (for <felipec@nysa.(none)>) not allowed
2) Only full name
fatal: unable to auto-detect email address (got 'felipec@nysa.(none)')
3) Full name + fqdm
Who should the emails appear to be from?
[Felipe Contreras <felipec@nysa.felipec.org>]
4) Full name + EMAIL
Who should the emails appear to be from?
[Felipe Contreras <felipe.contreras@gmail.com>]
5) User configured
6) GIT_COMMITTER
7) GIT_AUTHOR
All these are the same as 4)
After this patch:
1) 2) won't change: git send-email would still die
4) 5) 6) 7) will change: git send-email won't ask the user
This is good, that's what we would expect, because the identity is
explicit.
3) will change: git send-email won't ask the user
This is bad, because we will try with an address such as
'felipec@nysa.felipec.org', which is most likely not what the user
wants, but the user will get warned by default (confirm=auto), and if
not, most likely the sending won't work, which the user would readily
note and fix.
The worst possible scenario is that such mail address does work, and the
user sends an email from that address unintentionally, when in fact the
user expected to correct that address in the prompt. This is a very,
very, very unlikely scenario, with many dependencies:
1) No configured user.name/user.email
2) No specified $EMAIL
3) No configured sendemail.from
4) No specified --from argument
5) A fully qualified domain name
6) A full name in the geckos field
7) A sendmail configuration that allows sending from this domain name
8) confirm=never, or
8.1) confirm configuration not hitting, or
8.2) Getting the error, not being aware of it
9) The user expecting to correct this address in the prompt
In a more likely scenario where 7) is not the case (can't send from
nysa.felipec.org), the user will simply see the mail was not sent
properly, and fix the problem.
The much more likely scenario though, is where 5) is not the case
(nysa.(none)), and git send-email will fail right away like it does now.
So the likelihood of this affecting anybody seriously is very very slim,
and the chances of this affecting somebody slightly are still very
small. The vast majority, if not all, of git users won't be affected
negatively, and a lot will benefit from this.
Tests-by: Jeff King <peff@peff.net>
Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In the fallback check, used when Email::Valid is not available, the
extract_valid_address() uses $1 without checking for success of matching
regex. The $1 variable may still hold the result of previous match,
which is the address when email address was in '<>' or be undefined
otherwise.
Now if match fails undefined value is always returned to indicate error.
The same value is used by Email::Valid->address() in that case.
Previously 'foo@bar' address was rejected by Email::Valid and fallback,
but '<foo@bar>' was rejected by Email::Valid, but accepted by fallback.
Signed-off-by: Krzysztof Mazur <krzysiek@podlesie.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In some cases it is useful to add additional information after the
email address on the Cc: footer in a commit log, for instance:
"Cc: Stable kernel <stable@vger.kernel.org> #v3.4 v3.5 v3.6"
However, git-send-email refuses to pick up such an invalid address
when the Email::Valid perl module is available, or just uses the
whole line as the email address.
In sanitize_address(), remove everything after the email address, so
that the result is a valid email address that makes Email::Valid
happy.
Signed-off-by: Krzysztof Mazur <krzysiek@podlesie.net>
Tested-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
For raw subjects rfc2047 quoting is needed not only for non-ASCII characters,
but also for any possible rfc2047 in it.
Signed-off-by: Krzysztof Mazur <krzysiek@podlesie.net>
Signed-off-by: Jeff King <peff@peff.net>
The quote_rfc2047() always adds RFC2047 quoting. To avoid
quoting ASCII subjects, before calling quote_rfc2047()
subject must be tested for non-ASCII characters. This patch
introduces a new quote_subject() function, which performs
the test and calls quote_rfc2047 only if necessary.
Signed-off-by: Krzysztof Mazur <krzysiek@podlesie.net>
Signed-off-by: Jeff King <peff@peff.net>
The git-send-email always use RFC2047 subject quoting for
files with "broken" encoding - non-ASCII files without
Content-Transfer-Encoding, even for ASCII subjects. This is
harmless but unnecessarily ugly for people reading the raw
headers. This patch skips rfc2047 quoting when the subject
does not need it.
Signed-off-by: Krzysztof Mazur <krzysiek@podlesie.net>
Signed-off-by: Jeff King <peff@peff.net>
The commit "git-send-email: introduce compose-encoding" introduced
the compose-encoding option to specify the introduction email encoding
(--compose option), but the email Subject encoding was still hardcoded
to UTF-8.
Signed-off-by: Krzysztof Mazur <krzysiek@podlesie.net>
Signed-off-by: Jeff King <peff@peff.net>
The introduction email (--compose option) have encoding hardcoded to
UTF-8, but invoked editor may not use UTF-8 encoding.
The encoding used by patches can be changed by the "8bit-encoding"
option, but this option does not have effect on introduction email
and equivalent for introduction email is missing.
Added compose-encoding command line option and sendemail.composeencoding
configuration option specify encoding of introduction email.
Signed-off-by: Krzysztof Mazur <krzysiek@podlesie.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We may pick up additional recipients from the format-patch output
files we are sending, in which case it is perfectly valid to leave
the @initial_to empty when the prompt asks. We may want to start
a new discussion thread without replying to anything, and it is
valid to leave $initial_reply_to empty.
An earlier update to avoid y@example.com stuffed in address fields
did not take these two cases into account.
Signed-off-by: Stephen Boyd <bebarino@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Validate interactive input to "git send-email" to avoid common
mistakes such as saying "y<RETURN>" to sender mail address whose
prompt is given with a correctly guessed default.
* jc/send-email-reconfirm:
send-email: validate & reconfirm interactive responses
People answer 'y' to "Who should the emails appear to be from?" and
'n' to "Message-ID to be used as In-Reply-To for the first email?"
for some unknown reason. While it is possible that your local
username really is "y" and you are sending the mail to your local
colleagues, it is possible, and some might even say it is likely,
that it is a user error.
Fortunately, our interactive prompter already has input validation
mechanism built-in. Enhance it so that we can optionally reconfirm
and allow the user to pass an input that does not validate, and
"softly" require input to the sender, in-reply-to, and recipient to
contain "@" and "." in this order, which would catch most cases of
mistakes.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The RFC2047 unquoting, used to parse email addresses in From and Cc
headers, is broken in several ways:
* It erroneously substitutes ' ' for '_' in *the whole* header, even
outside the quoted field. [Noticed by Christoph.]
* It is too liberal in its matching, and happily matches the start
of one quoted chunk against the end of another, or even just
something that looks like such an end. [Noticed by Junio.]
* It fundamentally cannot cope with encodings that are not a
superset of ASCII, nor several (incompatible) encodings in the
same header.
This patch fixes the first two by doing a more careful decoding of
the outer quoting (e.g. "=AB" to represent an octet whose value is
0xAB). Fixing the fundamental issues is left for a future, more
intrusive, patch.
Noticed-by: Christoph Miebach <christoph.miebach@web.de>
Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Thomas Rast <trast@student.ethz.ch>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The sendemail.multiedit variable is meant to be a boolean.
However, it is not marked as such in the code, which means
we store its value literally. Thus in the do_edit function,
perl ends up coercing it to a boolean value according to
perl rules, not git rules. This works for "0", but "false",
"no", or "off" will erroneously be interpreted as true.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
