Fix for #3067

Shouldn't be moved to 4.1


myisam/mi_check.c:
  only set key_map if necessary

myisam/mi_check.c

@@ -1247,6 +1247,7 @@ int mi_repair(MI_CHECK *param, register MI_INFO *info,
     That is what the next line is for... (serg)
   */
 
+  if (param->testflag & T_CREATE_MISSING_KEYS)
     share->state.key_map= ((((ulonglong) 1L << share->base.keys)-1) &
 			   param->keys_in_use);