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
# mock out util.makedate() to supply testable values
from __future__ import absolute_import
import os
from mercurial import pycompat
from mercurial.utils import dateutil
def mockmakedate():
filename = os.path.join(os.environ['TESTTMP'], 'testtime')
try:
with open(filename, 'rb') as timef:
time = float(timef.read()) + 1
except IOError:
time = 0.0
with open(filename, 'wb') as timef:
timef.write(pycompat.bytestr(time))
return (time, 0)
dateutil.makedate = mockmakedate