Might it make sense to skip-decorate those tests which require cross-filesystem? Put a test above the TestMove definition which compares tempfile.gettempdir() and os.path.dirname(__file__).

I don't know of an out-of-the-box function to see if two paths are on the same filesystem; I suppose one approach would be to walk up the directory tree of each, checking ismount. (Looks like somebody's tried it: http://stackoverflow.com/questions/1138383/python-get-mount-point-on-windows-or-linux)