tests/sitecustomize.py

destutil: add the ability to specify a search space for rebase destination

In the 'hg pull --rebase', we don't want to pick a rebase destination unrelated
to the pull, we lay down basic infrastructure to allow such restriction on
stable (before 3.8 release) in this case. See issue 5214 for details.

Actual usage and test will be in the next patch.

from __future__ import absolute_import
import os

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

        # uuid is better, but not available in Python 2.4.
        covpath = os.path.join(os.environ['COVERAGE_DIR'],
                               'cov.%s' % random.randrange(0, 1000000000000))
        cov = coverage.coverage(data_file=covpath, auto_data=True)
        cov._warn_no_data = False
        cov._warn_unimported_source = False
        cov.start()
    except ImportError:
        pass