patch: don't produce a traceback in case of invalid diff content, a warning is enough.
patch: don't produce a traceback in case of invalid diff content, a warning is enough.

Also, skip the patch renderer if it didn't produce any 'diffs'.


git-svn-id: 0d96b0c1a6983ccc08b3732614f4d6bfcf9cbb42@9711 af82e41b-90c4-0310-8c96-b1721e28e2e2

rbaumg/trac,rbaumg/trac,rbaumg/trac,rbaumg/trac