Fix st2 execution tail message when there are no executions in DB
Fix st2 execution tail message when there are no executions in DB

nzlosh/st2,StackStorm/st2,nzlosh/st2,StackStorm/st2,nzlosh/st2,Plexxi/st2,Plexxi/st2,nzlosh/st2,StackStorm/st2,StackStorm/st2,Plexxi/st2,Plexxi/st2