reachableroots: return NULL if we're throwing an exception
Based on my reading of [0] and surrounding sections, if we want an
exception to be properly raised when something goes wrong in the C
code, we need to make sure we return NULL here. Do so.
https://docs.python.org/2/extending/extending.html#back-to-the-example
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