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
#!/usr/bin/env python3
#
# An example FastCGI script for use with flup, edit as necessary
# Path to repo or hgweb config to serve (see 'hg help hgweb')
config = b"/path/to/repo/or/config"
# Uncomment and adjust if Mercurial is not installed system-wide
# (consult "installed modules" path from 'hg debuginstall'):
# import sys; sys.path.insert(0, "/path/to/python/lib")
# Uncomment to send python tracebacks to the browser if an error occurs:
# import cgitb; cgitb.enable()
from mercurial import demandimport
demandimport.enable()
from mercurial.hgweb import hgweb
from flup.server.fcgi import WSGIServer
application = hgweb(config)
WSGIServer(application).run()