man: fix display of keys which appear in two sections in directive index

When an index key appeared in multiple sections (e.g.
CPUAffinity= was present in both "SYSTEM MANAGER DIRECTIVES"
and "UNIT DIRECTIVES"), when lxml was used, the key would
be not be displayed in all but one of those sections, and
only an empty <term/> element would be present. This
happens because lxml allows only one parent for each node,
and when the same formatted element was used in multiple places,
it was actually moved between them. Fix this by making a copy
of the element. The bug was present since lxml support was
introduced.

Also fix some indentation issues.

make-directive-index.py

@@ -21,6 +21,7 @@ import sys
 import collections
 import re
 from xml_helper import *
+from copy import deepcopy
 
 TEMPLATE = '''\
 <refentry id="systemd.directives" conditional="HAVE_PYTHON">
@@ -226,19 +227,20 @@ def _make_section(template, name, directives, formatting):
     for varname, manpages in sorted(directives.items()):
         entry = tree.SubElement(varlist, 'varlistentry')
         term = tree.SubElement(entry, 'term')
-        term.append(formatting[varname])
+        display = deepcopy(formatting[varname])
+        term.append(display)
 
         para = tree.SubElement(tree.SubElement(entry, 'listitem'), 'para')
 
         b = None
         for manpage, manvolume in sorted(set(manpages)):
-                if b is not None:
-                        b.tail = ', '
-                b = tree.SubElement(para, 'citerefentry')
-                c = tree.SubElement(b, 'refentrytitle')
-                c.text = manpage
-                d = tree.SubElement(b, 'manvolnum')
-                d.text = manvolume
+            if b is not None:
+                b.tail = ', '
+            b = tree.SubElement(para, 'citerefentry')
+            c = tree.SubElement(b, 'refentrytitle')
+            c.text = manpage
+            d = tree.SubElement(b, 'manvolnum')
+            d.text = manvolume
         entry.tail = '\n\n'
 
 def _make_colophon(template, groups):
@@ -264,7 +266,7 @@ def _make_page(template, directive_groups, formatting):
     }
     """
     for name, directives in directive_groups.items():
-            _make_section(template, name, directives, formatting)
+        _make_section(template, name, directives, formatting)
 
     _make_colophon(template, directive_groups.values())