tests/svnurlof.py

tests: replace some `python` by `"$PYTHON"` to not only use Python 2

I deleted my `python` binary as a test and a few tests started
failing.

Differential Revision: https://phab.mercurial-scm.org/D10250

from __future__ import absolute_import, print_function
import sys

from mercurial import (
    pycompat,
    util,
)


def main(argv):
    enc = util.urlreq.quote(pycompat.sysbytes(argv[1]))
    if pycompat.iswindows:
        fmt = 'file:///%s'
    else:
        fmt = 'file://%s'
    print(fmt % pycompat.sysstr(enc))


if __name__ == '__main__':
    main(sys.argv)