tests/sitecustomize.py

config: clean up message about ignored untrusted config

The error message relied on Python's default formatting of arguments
to an Exception's constructor. Let's try to make it a little more
readable for users.

Differential Revision: https://phab.mercurial-scm.org/D9352

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