tests/sitecustomize.py

repo: don't look up context for tip node if it's not needed

We were doing repo['tip'].node() or similar in a few places where
repo.changelog.tip() would be enough.

Differential Revision: https://phab.mercurial-scm.org/D4781

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