engine: fix broken message lookup

- Fixed issue where certain combinations of message keys
where not being included in the message map.

Change-Id: Id4ef98170fede29fa97dd9d8c839cc96671e2839
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1003775
Signed-off-by: Alexander Wels <awels@redhat.com>