range-diff: output ## Notes ## header

When notes were included in the output of range-diff, they were just
mashed together with the rest of the commit message. As a result, users
wouldn't be able to clearly distinguish where the commit message ended
and where the notes started.

Output a `## Notes ##` header when notes are detected so that notes can
be compared more clearly.

Note that we handle case of `Notes (<ref>): -> ## Notes (<ref>) ##` with
this code as well. We can't test this in this patch, however, since
there is currently no way to pass along different notes refs to `git
log`. This will be fixed in a future patch.

Signed-off-by: Denton Liu <liu.denton@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

range-diff.c

@@ -144,6 +144,12 @@ static int read_patches(const char *range, struct string_list *list)
 				strbuf_addstr(&buf, line);
 				strbuf_addstr(&buf, "\n\n");
 				strbuf_addstr(&buf, " ## Commit message ##\n");
+			} else if (starts_with(line, "Notes") &&
+				   line[strlen(line) - 1] == ':') {
+				strbuf_addstr(&buf, "\n\n");
+				/* strip the trailing colon */
+				strbuf_addf(&buf, " ## %.*s ##\n",
+					    (int)(strlen(line) - 1), line);
 			} else if (starts_with(line, "    ")) {
 				p = line + len - 2;
 				while (isspace(*p) && p >= line)

t/t3206-range-diff.sh

@@ -516,10 +516,10 @@ test_expect_success 'range-diff compares notes by default' '
 	2:  $(test_oid t2) = 2:  $(test_oid u2) s/4/A/
 	3:  $(test_oid t3) = 3:  $(test_oid u3) s/11/B/
 	4:  $(test_oid t4) ! 4:  $(test_oid u4) s/12/B/
-	    @@ Metadata
+	    @@ Commit message
 	    Z
-	    Z ## Commit message ##
-	    Z    s/12/B/
+	    Z
+	    Z ## Notes ##
 	    -    topic note
 	    +    unmodified note
 	    Z
@@ -543,17 +543,17 @@ test_expect_success 'format-patch --range-diff compares notes by default' '
 	grep "= 3: .* s/11/B" 0000-* &&
 	grep "! 4: .* s/12/B" 0000-* &&
 	sed s/Z/\ /g >expect <<-EOF &&
-	    @@ Metadata
+	    @@ Commit message
 	    Z
-	    Z ## Commit message ##
-	    Z    s/12/B/
+	    Z
+	    Z ## Notes ##
 	    -    topic note
 	    +    unmodified note
 	    Z
 	    Z ## file ##
 	    Z@@ file: A
 	EOF
-	sed "/@@ Metadata/,/@@ file: A/!d" 0000-* >actual &&
+	sed "/@@ Commit message/,/@@ file: A/!d" 0000-* >actual &&
 	test_cmp expect actual
 '