Sometimes when a Repo is merged, issue links no longer correspond to the same title (i.e. if '[fake_user/fake_project] fake_issue' gets merged into a RedHat git repo, it becomes '[red-hat/fake_project] fake_issue' but the issue link remains the same. This causes an issue when we are trying to match upstream/downstream issues.

The proposed fix is to first check for a direct match or an ID match as before. But if that does not return anything check to see if the upstream titles match directly (i.e. even if [red-hat/fake_project] don't match, check if fake_issue is in the downstream title. If it is, spit out a warning and assume they are supposed to be matched.

Other fixes in this PR:
* Check comments of an issue if it has been marked as a duplicate of another issue (skip if this is the case)
* Assert issue ID should be a string