When creating a new environment, if the default `template_dirs` is kept, arrange for the run-time default to be used, i.e. don't hard-code that default in the TracIni. Closes #3904.
When creating a new environment, if the default `template_dirs` is kept, arrange for the run-time default to be used, i.e. don't hard-code that default in the TracIni. Closes #3904.


git-svn-id: eda3d06fcef731589ace1b284159cead3416df9b@3914 af82e41b-90c4-0310-8c96-b1721e28e2e2

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