This patch looks good to me.  Note that the reason for the basedir change is that the test would fail if run from a build directory which hadn't been installed.  An implication of this is that 'doc_loc' is None most of the time when the other tests are run, meaning that this new test is the only one that consistently tests the body of getdocloc.  I think that method could use some more tests, but that is a separate issue.