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: eda3d06fcef731589ace1b284159cead3416df9b@9400 af82e41b-90c4-0310-8c96-b1721e28e2e2

netjunki/trac-Pygit2,jun66j5/trac-ja,jun66j5/trac-ja,jun66j5/trac-ja,walty8/trac,walty8/trac,netjunki/trac-Pygit2,netjunki/trac-Pygit2,walty8/trac,jun66j5/trac-ja,walty8/trac