Fix bug#55699 - Assertion failure in innodb plugin with large number of threads

      
Fix a debug assertion that was missed in svnrev:2380 (fix for Bug# 35352).

Approved by Marko on IRC

storage/innodb_plugin/trx/trx0undo.c

@@ -1938,7 +1938,8 @@ trx_undo_update_cleanup(
 
 		UT_LIST_ADD_FIRST(undo_list, rseg->update_undo_cached, undo);
 	} else {
-		ut_ad(undo->state == TRX_UNDO_TO_PURGE);
+		ut_ad(undo->state == TRX_UNDO_TO_PURGE
+		      || undo->state == TRX_UNDO_TO_FREE);
 
 		trx_undo_mem_free(undo);
 	}