tests: stabilize test-subrepo-svn.t on Windows
This partially reverts 991e4404e910, because the URL form of `C:\...` gets
escaped to `C%3A/...`, which breaks the substitution of $TESTTMP.
The forget command on 'notafile*' errored out with:
notafile*: The filename, directory name, or volume label syntax is incorrect
which I think is because '*' isn't a legal character in a file name (though I
can't trigger this directly from MSYS or cmd.exe for some reason).
Differential Revision: https://phab.mercurial-scm.org/D7816
{
"conduit_uri": "https://phab.mercurial-scm.org/api",
"repository.callsign": "HG",
"arc.land.onto.default": "@",
"base": "hg:.^"
}