run-tests: set HGMODULEPOLICY for --pure Without this, my python 2.6 virtualenv test run with --pure and --local fails with: + ImportError: Python minor version mismatch: The Mercurial extension modules were compiled with Python 2.7.8, but Mercurial is currently using Python with sys.hexversion=33950192: Python 2.6.9 (unknown, Apr 13 2016, 12:40:12) + [GCC 4.9.2 20141101 (Red Hat 4.9.2-1)] + at: ~/hg/py26/bin/python