issue ER_USER_IS_BLOCKED also for non-existent users

following the same masquerading logic

sql/sql_acl.cc

@@ -12828,15 +12828,6 @@ static bool find_mpvio_user(MPVIO_EXT *mpvio)
 
   ACL_USER *user= find_user_or_anon(sctx->host, sctx->user, sctx->ip);
 
-  if (user && user->password_errors >= max_password_errors && !ignore_max_password_errors(user))
-  {
-    mysql_mutex_unlock(&acl_cache->lock);
-    my_error(ER_USER_IS_BLOCKED, MYF(0));
-    general_log_print(mpvio->auth_info.thd, COM_CONNECT,
-      ER_THD(mpvio->auth_info.thd, ER_USER_IS_BLOCKED));
-    DBUG_RETURN(1);
-  }
-
   if (user)
     mpvio->acl_user= user->copy(mpvio->auth_info.thd->mem_root);
 
@@ -12873,6 +12864,15 @@ static bool find_mpvio_user(MPVIO_EXT *mpvio)
     mpvio->make_it_fail= true;
   }
 
+  if (mpvio->acl_user->password_errors >= max_password_errors &&
+      !ignore_max_password_errors(mpvio->acl_user))
+  {
+    my_error(ER_USER_IS_BLOCKED, MYF(0));
+    general_log_print(mpvio->auth_info.thd, COM_CONNECT,
+      ER_THD(mpvio->auth_info.thd, ER_USER_IS_BLOCKED));
+    DBUG_RETURN(1);
+  }
+
   /* user account requires non-default plugin and the client is too old */
   if (mpvio->acl_user->auth->plugin.str != native_password_plugin_name.str &&
       mpvio->acl_user->auth->plugin.str != old_password_plugin_name.str &&