Fixed ROOT_CGROUPS_Write test.
Fixed ROOT_CGROUPS_Write test.

Review: https://reviews.apache.org/r/18532

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