devtools: check coverity and bugzilla tags

Let's try to check for discrepancies in coverity and bugzilla tags.
The contributing guide specifies that:
- for coverity issues, the tag is 'Coverity issue:'
- for bugzilla issues, the tag is 'Bugzilla ID:'

Signed-off-by: David Marchand <david.marchand@redhat.com>
Acked-by: Kevin Traynor <ktraynor@redhat.com>