Raise exception on invalid pipeline cache

lib/gitlab/etag_caching/store.rb

@@ -25,6 +25,8 @@ module Gitlab
       end
 
       def redis_key(key)
+        raise 'Invalid key' unless Gitlab::EtagCaching::Router.match(key)
+        
         "#{REDIS_NAMESPACE}#{key}"
       end
     end