admin: Made `trac-admin` more user-friendly when the environment has not been created yet.
admin: Made `trac-admin` more user-friendly when the environment has not been created yet.

Closes #8920.


git-svn-id: 0d96b0c1a6983ccc08b3732614f4d6bfcf9cbb42@9400 af82e41b-90c4-0310-8c96-b1721e28e2e2

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