i went to change Bug 164790 when it was first filed by: - unlocking the bug - setting product to Gentoo Linux - selecting "Reassign bug to default assignee of selected component" option however, someone else did so before me but instead of getting the normal "Mid-air collision" notice, i got a nice internal bugzilla error
https://bugzilla.mozilla.org/enter_bug.cgi?product=Bugzilla (and even there noone will tell you much without the actual error message provided)