tests/sitecustomize.py

mergestate: raise structured exception for unsupported merge records

We're going to catch this exception in 'hg summary' to print a better error
message.

This code is pretty untested, so there are no changes to test output. In
upcoming patches we're going to test the output more thoroughly.

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