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