Add a work around for listener api test case race.
Add a work around for listener api test case race.

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