Actually abort on unrecognized platforms
Actually abort on unrecognized platforms

Change-Id: I4c908b4eea31bf9acc3397591a080df9c60b22bf

openstack/sahara-image-elements,bigfootproject/sahara-image-elements,uladz/sahara-image-elements,uladz/sahara-image-elements,openstack/sahara-image-elements,crobby/sahara-image-elements,bigfootproject/sahara-image-elements,crobby/sahara-image-elements