tests/sitecustomize.py

context: rename local 'attr' to 'attr_'

In the next diff we're going to import mercurial.thirdparty.attr, and pyflakes
complains about this if this rename isn't done.

Differential Revision: https://phab.mercurial-scm.org/D897

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