The result of max(time) group by a constant value is wrong

[lilinghai]

Mini reproduce:

create table t1(a timestamp,b int);
alter table t1 set tiflash replica 1;
insert into t1 values("2018-11-22 16:55:24",1);
insert into t1 values("2018-11-23 00:55:24",1);
select max(a) from t1 group by "a";  -- expect 2018-11-23 00:55:24 ; but got 2018-11-22 16:55:24

TiFlash
Release Version: v5.0.0-nightly-53-g37740f794
Edition: Community
Git Commit Hash: 37740f7
Git Branch: master
UTC Build Time: 2021-04-15 10:16:48
Profile: RELWITHDEBINFO

Raft Proxy
Git Commit Hash: 3bb85b07bb9d9a5da2a3595457c3587183ff36d9
Git Commit Branch: HEAD
UTC Build Time: 2021-04-15 09:56:37
Rust Version: rustc 1.51.0-nightly (bc39d4d9c 2021-01-15)
Storage Engine: tiflash
Prometheus Prefix: tiflash_proxy_
Profile: release

[windtalker]

The is triggered by unexpected time_zone cast, the trigger condition is:

1. TiDB push down a in-consistent type in DAG request(by in-consistent I mean the return type in DAG request is not the same as the running time type of TiFlash, take issue Randgen: block schema mismatch  #1567 for example)
2. The return column contains a timestamp column and current timezone is not UTC.