store the runtime, unset the callback at shutdown r=dveditz sr=jst a=asa git-svn-id: svn://10.0.0.236/trunk@174245 18797224-902f-48f8-a5cc-f745e15eee43
store the runtime, unset the callback at shutdown r=dveditz sr=jst a=asa git-svn-id: svn://10.0.0.236/trunk@174245 18797224-902f-48f8-a5cc-f745e15eee43