bug trackers.

Examples:

* "[#nnn] Worked on this issue"
* "[#nnn, #mmm] Worked on these"
* "[#nnn #mmm] Working some more"

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@2854 e93f8b46-1217-0410-a6f0-8f06a7374b81