No notification email for previous owner on owner change

[Ryan Ollos <ry...@wandisco.com>]

I worked up a patch for the Trac core that fixes the problem in which the
previous owner is not notified when a ticket is reassigned. This is a
longstanding issue in Trac, and I think it has been open for far too long
relative to the usability impact.

I raise the issue here in case anyone might have an interest in reviewing
and helping me improve the patch, to increase the possibility of
integration to the Trac core. If you have specific comments on how to
improve the code, please comment directly on the Trac ticket or on the
changeset, so that we can keep the feedback organized and visible to the
Trac core developers.

http://trac.edgewall.org/ticket/2311#comment:19