Requires that the changelist is associated with a bug. This check is stricter than the one in depot_tools/presubmit_canned_checks.py since it fails the presubmit if the bug field is missing or doesn't contain a bug reference. This supports both 'BUG=' and 'Bug:' since we are in the process
(input_api, output_api)
source not stored for this graph (policy: none)
no test coverage detected