automatic merge with 5.1-release

storage/maria/ma_pagecache.c

@@ -1046,7 +1046,6 @@ static inline void dec_counter_for_resize_op(PAGECACHE *pagecache)
                         ("thread %ld", last_thread->next->id));
     pagecache_pthread_cond_signal(&last_thread->next->suspend);
   }
-  DBUG_ASSERT((longlong) pagecache->cnt_for_resize_op >= 0);
 #else
   pagecache->cnt_for_resize_op--;
 #endif