tests/sitecustomize.py

pathutil: add doctests for canonpath()

This is a followup to f445b10dc7fb.  Since there's no way to ensure that more
drive letters than C: exist, this seems like the only way to test it.  This is
enough to catch the f445b10dc7fb scenario, as well as CWD outside of the repo
when the path isn't prefixed with path/to/repo.

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