* Prevent merge messages from being sorted to the top of email chains
Gitea will currrently resend the same message-id for the closed/merged/reopened
messages for issues. This will cause the merged message to leap to the top of an
email chain and become out of sync.
This PR adds specific suffices for these actions.
Fix#18560
Signed-off-by: Andrew Thornton <art27@cantab.net>
* add test
Signed-off-by: Andrew Thornton <art27@cantab.net>