notification enhancement for mentions in pull request diff viewer

The pull request diff viewer allows me to add comments to individual lines of code. If I add a mention to the comment, that person will receive a notification email. This is great, but one thing is missing:

If I am commenting on a line of the code and that line is an added or deleted line and the developer who made that change is not the same as the developer who submitted the pull request, I want a mention of that developer to be in the comment edit box when I first create the comment.

The attached example is what I expect to happen assuming "e18976" was the developer who modified line 24 of the file.

(I still need blame info for each line, but this comment change is more important because it will make mixed code reviews work well)

Alternatively, a checkbox or something which will "copy committers" which would either harvest the ID of the person(s) involved in the selected lines and inject into the regular @ style mention, or harvest the email address from the blame information and inject them as part of the notification object assembly. That might be a simpler way to handle this without having to pre-fill data into comment box.