Fixed flaky SchedulerDriverEventTest.SubscribedSchedulerFailover test.
Fixed flaky SchedulerDriverEventTest.SubscribedSchedulerFailover test.

verizonlabs/mesos,abudnik/mesos,craimbert/mesos,Gilbert88/mesos,verizonlabs/mesos,jpeach/mesos,chhsia0/mesos,Gilbert88/mesos,abudnik/mesos,andschwa/mesos,asamerh4/mesos,reneploetz/mesos,dforsyth/mesos,reneploetz/mesos,Gilbert88/mesos,jpeach/mesos,asamerh4/mesos,Aman-Jain-14/customizedMesos,gsantovena/mesos,asamerh4/mesos,Aman-Jain-14/customizedMesos,neilconway/mesos,gsantovena/mesos,craimbert/mesos,asamerh4/mesos,asamerh4/mesos,dforsyth/mesos,dforsyth/mesos,abudnik/mesos,chhsia0/mesos,chhsia0/mesos,reneploetz/mesos,kaysoky/mesos,andschwa/mesos,yuquanshan/customizedMesos,kaysoky/mesos,gsantovena/mesos,zmalik/mesos,dforsyth/mesos,jpeach/mesos,yuquanshan/customizedMesos,kaysoky/mesos,chhsia0/mesos,Aman-Jain-14/customizedMesos,reneploetz/mesos,verizonlabs/mesos,jpeach/mesos,jpeach/mesos,zmalik/mesos,andschwa/mesos,andschwa/mesos,verizonlabs/mesos,neilconway/mesos,andschwa/mesos,Gilbert88/mesos,andschwa/mesos,dforsyth/mesos,craimbert/mesos,Gilbert88/mesos,gsantovena/mesos,Gilbert88/mesos,jpeach/mesos,gsantovena/mesos,Aman-Jain-14/customizedMesos,gsantovena/mesos,Aman-Jain-14/customizedMesos,Gilbert88/mesos,asamerh4/mesos,zmalik/mesos,verizonlabs/mesos,reneploetz/mesos,dforsyth/mesos,reneploetz/mesos,zmalik/mesos,verizonlabs/mesos,dforsyth/mesos,abudnik/mesos,zmalik/mesos,kaysoky/mesos,craimbert/mesos,kaysoky/mesos,chhsia0/mesos,neilconway/mesos,Aman-Jain-14/customizedMesos,neilconway/mesos,chhsia0/mesos,craimbert/mesos,neilconway/mesos,gsantovena/mesos,abudnik/mesos,chhsia0/mesos,neilconway/mesos,craimbert/mesos,yuquanshan/customizedMesos,yuquanshan/customizedMesos,zmalik/mesos,kaysoky/mesos,reneploetz/mesos,yuquanshan/customizedMesos,andschwa/mesos,kaysoky/mesos,zmalik/mesos,verizonlabs/mesos,Aman-Jain-14/customizedMesos,yuquanshan/customizedMesos,abudnik/mesos,craimbert/mesos,jpeach/mesos,abudnik/mesos,asamerh4/mesos,neilconway/mesos,yuquanshan/customizedMesos