tests/filtertmp.py

tests: fix bashism to load helpers.sh

`source` isn't available at POSIX sh.

#!/usr/bin/env python
#
# This used to be a simple sed call like:
#
#  $ sed "s:$HGTMP:*HGTMP*:"
#
# But $HGTMP has ':' under Windows which breaks the sed call.
#
import sys, os

input = sys.stdin.read()
input = input.replace(os.sep, '/')
hgtmp = os.environ['HGTMP'].replace(os.sep, '/')
input = input.replace(hgtmp, '$HGTMP')
sys.stdout.write(input)