Notifications trigger on Contribution Comment update.

When a user updates a comment with a mention inside it will trigger the notification again.

I have been able to reproduce this issue once again:

When a user upvotes a comment with a mention inside, all mentioned users get the notification "you've been mentioned" again. I assume this also causes some issues on performance (more votes, more notifications as they double up with each mention and vote).

[appinteractive]

@sebako86 please take a look at my pull request on above.