Add support for customizable changelog formats

This adds a new option, changelog_format, which allows specifying the
full format of generated changelog entries.  This also deprecates use
of changelog_with_email, since it is a subset of a fully-customizable
changelog format.

src/tito/cli.py

@@ -710,7 +710,7 @@ class InitModule(BaseCliModule):
             out_f.write(
                 "default_tagger = %s\n" % 'tito.tagger.VersionTagger')
             out_f.write("changelog_do_not_remove_cherrypick = 0\n")
-            out_f.write("changelog_with_email = 1\n")
+            out_f.write("changelog_format = %s %(ae)\n")
             out_f.close()
             print("   - wrote %s" % GLOBAL_BUILD_PROPS_FILENAME)
 

src/tito/tagger.py

@@ -146,25 +146,35 @@ class VersionTagger(object):
                 line = m.group(1)
         return line
 
-    def _changelog_email(self):
+
+    def _changelog_format(self):
         """
-        if you have set changelog_with_email in [globalconfig] set to 1, it will return
-        string '(%ae)'
+        If you have set changelog_format in [globalconfig], it will return
+        that string.  Otherwise, return one of two defaults:
+
+        - '%s (%ae)', if changelog_with_email is unset or evaluates to True
+        - '%s', if changelog_with_email is set and evaluates to False
         """
         result = ''
-        if (self.config.has_option("globalconfig", "changelog_with_email")
-            and self.config.get("globalconfig", "changelog_with_email")) or \
-            not self.config.has_option("globalconfig", "changelog_with_email"):
-            result = ' (%ae)'
+        if self.config.has_option("globalconfig", "changelog_format"):
+            result = self.config.get("globalconfig", "changelog_format")
+        else:
+            with_email = ''
+            if (self.config.has_option("globalconfig", "changelog_with_email")
+                and self.config.get("globalconfig", "changelog_with_email")) or \
+                not self.config.has_option("globalconfig", "changelog_with_email"):
+                with_email = ' (%ae)'
+            result = "%%s%s" % with_email
         return result
 
+
     def _generate_default_changelog(self, last_tag):
         """
         Run git-log and will generate changelog, which still can be edited by user
         in _make_changelog.
         """
-        patch_command = "git log --pretty='format:%%s%s'" \
-                         " --relative %s..%s -- %s" % (self._changelog_email(), last_tag, "HEAD", ".")
+        patch_command = "git log --pretty='format:%s'" \
+                         " --relative %s..%s -- %s" % (self._changelog_format(), last_tag, "HEAD", ".")
         output = run_command(patch_command)
         result = []
         for line in output.split('\n'):

tito.props.5.asciidoc

@@ -52,9 +52,16 @@ This option is used in project specific tito.props only, and allows that project
 tagger::
 This option is used in project specific tito.props only, and allows that project to override the default_tagger defined in rel-eng/tito.props.
 
+changelog_format::
+This option is used to control the formatting of entries when
+generating changelog entries.  The default value is "%s (%ae)".  See
+PRETTY FORMATS in git-log(1) for more information.
+
 changelog_with_email::
-If set to 0, then entries in changelog (subject of commits) are not followed by
-email of commiter. Default is 1.
+If set to 0, then entries in changelog (subject of commits) are not
+followed by email of commiter. Default is 1.  This option is
+deprecated and provided for backwards-compatibility only.  New
+configurations should consider changelog_format instead.
 
 changelog_do_not_remove_cherrypick::
 If set to 0, it will not remove from cherry picked commits the part "(cherry