Don't add 127.0.0.1 to resolv.conf twice
On systems with multiple IP addresses the update code could add
::1 and 127.0.0.1 multiple times.
Related: https://pagure.io/freeipa/issue/8275
Signed-off-by: Christian Heimes <cheimes@redhat.com>
Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>