Properly quote memcache.locking

config/config.sample.php

@@ -1043,7 +1043,7 @@ $CONFIG = array(
  * Memory caching backend for file locking
  * Because most memcache backends can clean values without warning using redis is recommended
  */
-'memcache.locking' => '\OC\Memcache\Redis',
+'memcache.locking' => '\\OC\\Memcache\\Redis',
 
 /**
  * This entry is just here to show a warning in case somebody copied the sample