Gerrit git cl: fix change-id appending.

Special case when the change description has no footers, but looks
like a footer.

R=machenbach@chromium.org,andybons@chromium.org
BUG=579176

Review URL: https://codereview.chromium.org/1812803002

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@299343 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/git_footers.py b/git_footers.py
index 1d4d4dd..4641f74 100755
--- a/git_footers.py
+++ b/git_footers.py
@@ -83,9 +83,13 @@
     if line == '' or line.isspace():
       break
     footer_lines.append(line)
+  else:
+    # The whole description was consisting of footers,
+    # which means those aren't footers.
+    footer_lines = []
   # footers order is from end to start of the message.
   footers = map(parse_footer, footer_lines)
-  if not all(footers):
+  if not footers or not all(footers):
     lines.append('')
     lines.append(change_id_line)
   else: