1.0.3dev: Set `base_url` in `EnvironmentStub` rather than directly assigning to `href` and `abs_href`. Refs #11245.


git-svn-id: http://trac.edgewall.org/intertrac/log:/branches/1.0-stable@13161 af82e41b-90c4-0310-8c96-b1721e28e2e2