Update statement not blocked by primary or unique lock in partition

[wjhuang2016]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

ref https://github.com/pingcap/tidb/issues/20692

func TestIssue20692(t *testing.T) {
    store := testkit.CreateMockStore(t)
    tk := testkit.NewTestKit(t, store)
    tk.MustExec("use test")
    tk.MustExec("drop table if exists t")
    tk.MustExec("create table t (id int primary key, v int, vv int, vvv int, unique key u0(id, v, vv)) partition by hash (id) partitions 1;")
    tk.MustExec("insert into t values(1, 1, 1, 1);")
    tk1 := testkit.NewTestKit(t, store)
    tk2 := testkit.NewTestKit(t, store)
    tk3 := testkit.NewTestKit(t, store)
    tk1.MustExec("begin pessimistic;")
    tk1.MustExec("use test")
    tk2.MustExec("begin pessimistic;")
    tk2.MustExec("use test")
    tk3.MustExec("begin pessimistic;")
    tk3.MustExec("use test")
    tk1.MustExec("delete from t where id = 1 and v = 1 and vv = 1;")
    stop1, stop2 := make(chan struct{}), make(chan struct{})
    go func() {
        tk2.MustExec("insert into t values(1, 2, 3, 4);")
        stop1 <- struct{}{}
        tk3.MustExec("update t set id = 10, v = 20, vv = 30, vvv = 40 where id = 1 and v = 2 and vv = 3;")
        stop2 <- struct{}{}
    }()
    tk1.MustExec("commit;")
    <-stop1

    // wait 50ms to ensure tk3 is blocked by tk2
    select {
    case <-stop2:
        t.Fail()
    case <-time.After(50 * time.Millisecond):
    }

    tk2.MustExec("commit;")
    <-stop2
    tk3.MustExec("commit;")
    tk3.MustQuery("select * from t;").Check(testkit.Rows("10 20 30 40"))
}

Change the table t from non-partition to partition

2. What did you expect to see? (Required)

Test passes.

3. What did you see instead (Required)

Test fails.

4. What is your TiDB version? (Required)

master