Merge 10.4 into 10.5

mysql-test/suite/versioning/r/alter.result

@@ -377,6 +377,11 @@ a	b
 2	NULL
 3	1
 4	2
+alter table t add c int, drop system versioning;
+select * from t;
+a	b	c
+3	1	NULL
+4	2	NULL
 create or replace table t (a int) with system versioning;
 insert into t values (1), (2), (3);
 delete from t where a<3;