Don't raise an internal error when granting an already granted permission or when adding a subject to a group when it was already part of that group. Fixes #3873.
Don't raise an internal error when granting an already granted permission or when adding a subject to a group when it was already part of that group. Fixes #3873.

git-svn-id: 0d96b0c1a6983ccc08b3732614f4d6bfcf9cbb42@5190 af82e41b-90c4-0310-8c96-b1721e28e2e2

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