yum-minimal : better cleanup of initial yum failure
yum-minimal : better cleanup of initial yum failure

If the initial yum install into the chroot fails, we can leave behind
a lockfile and an incorrectly modified rpmmacros.

Change this so we run the cleanup unconditionally.

Change-Id: Ia9f9c4c845e5f34d33ff9a4ab7226c9175283757

zioproto/diskimage-builder,switch-ch/diskimage-builder,switch-ch/diskimage-builder,openstack/diskimage-builder,openstack/diskimage-builder,zioproto/diskimage-builder