mod_python handler: Only release lock if it has been acquired.
mod_python handler: Only release lock if it has been acquired.

git-svn-id: 0d96b0c1a6983ccc08b3732614f4d6bfcf9cbb42@1978 af82e41b-90c4-0310-8c96-b1721e28e2e2

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