API change in Dalli v2.7 - see petergoldstein/dalli#424

Author: tomhughes

lib/openid/store/memcache.rb

@@ -66,7 +66,7 @@ def use_nonce(server_url, timestamp, salt)
         if result.is_a? String
           return !!(result =~ /^STORED/)
         else
-          return result == true
+          return !!(result)
         end
       end