Rakefile in docker-api-1.17.0 vs Rakefile in docker-api-1.18.0

@@ -42,13 +42,11 @@
           'PortBindings' => { '5000/tcp' => [{ 'HostPort' => '5000' }] }
         }
       )
       registry.start
       Rake::Task["spec"].invoke
-    rescue
-      # nothing
     ensure
-      registry.kill!.remove
+      registry.kill!.remove unless registry.nil?
     end
   end
 end
 
 desc 'Pull an Ubuntu image'