Ansible-core 2.16.4 appears to have a behavior change where it
will include the implicit localhost in hostvars, which means that
any location we iterate over hostvars and assume it's a real host
could throw an exception. To avoid that, add checks that the
variables we are about to access on the host exist.
Change-Id: Iff89da761e5f6748b454610a64c2fdd4f5e56a77
f88eb51b71