Comment 2 for bug 1456950

Another possibility: After the action, display a warning with an undo link.

   You have assigned this bug to {yourself|Mark Shuttleworth|whoever}.
   The assignee is responsible for developing a fix for this bug.
   If you do not have the authority and mandate to assign bugs, please [undo this change].

I'm sure the wording can be improved, especially for the last sentence.

I kind of like this idea; the undo functionality might turn out be useful for other things as well.