Fixed a test that leaked a child process.
Fixed a test that leaked a child process.

Review: https://reviews.apache.org/r/17673

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