1.0.3dev: Small refactoring to improve code clarity. Refs #11648.

The `decision` variable can only be `False` at this point in the code, so the conditional has been made more specific.


git-svn-id: http://trac.edgewall.org/intertrac/log:/branches/1.0-stable@13168 af82e41b-90c4-0310-8c96-b1721e28e2e2