bin/get-pick-list.sh: handle unofficial "broken by" tag

We have a number of cases were devs will use a tag "broken by".
While it's not something officially documented or recommended, checking
for it is trivial enough.

Cc: mesa-stable@lists.freedesktop.org
Reviewed-by: Juan A. Suarez <jasuarez@igalia.com>
Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
(cherry picked from commit 77ff0bfb)