Addition to fix for

BUG#25712 - insert delayed and check table run together report crashed
            tables
Fixed wrongly applied patch.

mysys/my_seek.c

@@ -58,7 +58,7 @@ my_off_t my_seek(File fd, my_off_t pos, int whence,
   {
     pthread_mutex_lock(&my_file_info[fd].mutex);
     newpos= lseek(fd, pos, whence);
-    pthread_mutex_lock(&my_file_info[fd].mutex);
+    pthread_mutex_unlock(&my_file_info[fd].mutex);
   }
   else
 #endif