TypeError: unsupported operand type s for : NoneType and NoneType

[dmarti]

How to Reproduce

While doing a GET operation on /changeset/26e036576133f07b15eeb4363bf993b67bf9eacb/tp, Trac issued an internal error.

This only happens for a changeset that only updates git submodules, for which "get_content_length" returns None (because there is no associated git blob).

(The Python error is "unsupported operand type(s) for +")

This is similar to the old ticket #3287 here.

Request parameters:

{ new : u 26e036576133f07b15eeb4363bf993b67bf9eacb ,  new_path : u /tp }

User agent: Mozilla/5.0 X11; U; Linux x86_64; en-US; rv:1.9.2.17 Gecko/20110428 Fedora/3.6.17-1.fc14 Firefox/3.6.17

System Information

Trac	0.12.1
Docutils	0.7
Genshi	0.6
GIT	1.7.3.4
psycopg2	2.2.2
Pygments	1.3.1
Python	2.6.6 r266:84292, Mar 6 2011, 17:53:48 br GCC 4.3.4
pytz	2010o
setuptools	0.6
Subversion	1.6.16 r1073529
jQuery	1.4.2

Enabled Plugins

BatchModify	0.8.0-trac0.12
FilteredTicketQuery	N/A
timingandestimationplugin	1.0.6
TracGit	0.12.0.6dev

Python Traceback

Traceback  most recent call last :
File  /usr/lib64/python2.6/site-packages/trac/web/main.py , line 511, in _dispatch_request
dispatcher.dispatch req
File  /usr/lib64/python2.6/site-packages/trac/web/main.py , line 237, in dispatch
resp   chosen_handler.process_request req
File  /usr/lib64/python2.6/site-packages/trac/versioncontrol/web_ui/changeset.py , line 352, in process_request
self._render_html req, repos, chgset, restricted, xhr, data
File  /usr/lib64/python2.6/site-packages/trac/versioncontrol/web_ui/changeset.py , line 586, in _render_html
diff_bytes   _estimate_changes old_node, new_node
File  /usr/lib64/python2.6/site-packages/trac/versioncontrol/web_ui/changeset.py , line 537, in _estimate_changes
return old_size new_size
TypeError: unsupported operand type s  for :  NoneType  and  NoneType