BuddyPress.org

Sorry, i didn’t see you’re using 1.2.7….
The line you search is this one
https://trac.buddypress.org/browser/tags/1.2.7/bp-themes/bp-default/comments.php#L100
note that comments.php is the only file where this line exist.
if you search for specific things, this is a good starting point:
http://etivite.com/groups/buddypress/hooks/