id	summary	reporter	owner	description	type	status	priority	component	severity	resolution	keywords	cc	release
10886	TypeError: unsupported operand type(s) for +: 'NoneType' and 'NoneType'	voznesensky@…	anonymous	"==== How to Reproduce ====
Commit a simple update in git submodule and try to view the change in trac.
==== Python Traceback ====
Most recent call last:

File ""/usr/lib/python2.7/dist-packages/trac/web/main.py"", line 522, in _dispatch_request
  dispatcher.dispatch(req)
File ""/usr/lib/python2.7/dist-packages/trac/web/main.py"", line 243, in dispatch
  resp = chosen_handler.process_request(req)
File ""/usr/lib/python2.7/dist-packages/trac/versioncontrol/web_ui/changeset.py"", line 352, in process_request
  self._render_html(req, repos, chgset, restricted, xhr, data)
File ""/usr/lib/python2.7/dist-packages/trac/versioncontrol/web_ui/changeset.py"", line 586, in _render_html
  diff_bytes += _estimate_changes(old_node, new_node)
File ""/usr/lib/python2.7/dist-packages/trac/versioncontrol/web_ui/changeset.py"", line 537, in _estimate_changes
  return old_size + new_size
"	defect	new	normal	SELECT A HACK	normal