bug 812804 and abusing the urgency tag.

[Gianfranco Costamagna]

Hi Christopher and Nobuhiro, please don't use urgency critical for normal bugs.

This prevents useful testing from unstable users, and might be source of 
troubles
for stretch users.

Urgency medium (the default) should have been the best value here.
(high is for security, critical for serious breakages, not for a 1-month-old 
end user application issue)

cheers,

Gianfranco