Revert "Don't die when yum fails."
Revert "Don't die when yum fails."

This reverts commit 2babf3963f4eea8558b0c287c51e6faeb7069c70.

This breaks oslo.messaging jobs:
http://logs.openstack.org/32/265932/1/check/gate-oslo.messaging-dsvm-functional-amqp1-centos7/f5f3eb9/console.html#_2016-01-11_20_03_33_162

@kgiusti reports that PIPESTATUS[0] is always 1 on his centos7 box

Change-Id: I013c22a3545f22c79a0616b4a98622d41bb17d77

bigswitch/devstack,dirkmueller/devstack,noironetworks/devstack,group-policy/devstack,richliu/devstack,richliu/devstack,dirkmueller/devstack,mssumanth/devstack,group-policy/devstack,noironetworks/devstack,mssumanth/devstack,openstack-dev/devstack,openstack-dev/devstack,dtroyer/devstack,samgoon/devstack,nawawi/openstack,bigswitch/devstack,bswartz/devstack,samgoon/devstack,bswartz/devstack,nawawi/openstack,Mahito/devstack,Mahito/devstack,dtroyer/devstack