Regarding the patch:
You're using db.msg.get(firstmessageid, 'author'), but the issue
itself already has an author attribute, which I think should be
used instead.

Rationale:
1. The user might have created the issue without a message. If now the
   user provides more details it should not be chatting, but if someone
   else reacts, chatting should be set.
2. The user might have unlinked (removed) the first message from the
   issue (e.g. to provide a better initial description)
3. Don't access parts of the database you don't really need :)