perf: ensure HGRCPATH is exported on Windows
After dropping the garbage collector hack, `hg perfstartup` started yelling
about not being able to import the evolve extension, which I have in my user
config. Launching `env` shows that an empty HGRCPATH isn't exported to the
environment. Since `env` doesn't quote, I have no idea if the variable is
trimmed, but Mercurial doesn't complain when processing it.
#!/usr/bin/env python
from __future__ import absolute_import, print_function
import errno
import os
import sys
for f in sys.argv[1:]:
try:
print(f, '->', os.readlink(f))
except OSError as err:
if err.errno != errno.EINVAL:
raise
print(f, '->', f, 'not a symlink')
sys.exit(0)