tests/sitecustomize.py

hghave: make error output easier to diagnose

I had a typo that meant the new bash check was throwing an exception
(due to a missing argument), but it was very hard to diagnose without
this change.

Differential Revision: https://phab.mercurial-scm.org/D10733

from __future__ import absolute_import
import os

if os.environ.get('COVERAGE_PROCESS_START'):
    try:
        import coverage
        import uuid

        covpath = os.path.join(
            os.environ['COVERAGE_DIR'], 'cov.%s' % uuid.uuid1()
        )
        cov = coverage.coverage(data_file=covpath, auto_data=True)
        cov._warn_no_data = False
        cov._warn_unimported_source = False
        cov.start()
    except ImportError:
        pass