Fixed broken cni isolator test on centos7.
Fixed broken cni isolator test on centos7.

Review: https://reviews.apache.org/r/48989/

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