Restore /etc/hosts after upstream_centos tests and default CONTAINERTEST to 0 only if not set.
The upstream centos tests do some fiddling with /etc/hosts probably so that the hostname really resolves to the localhost interface for testing services.
We want to restore /etc/hosts file to a state as if the centos_upstream_tests had never run.
Happened to notice CONTAINERTEST is reset hard to 0 here. Surely should be conditional on it not being set.
Edited by Steve Traylen