fix test_node_request_snapshot_reject_merge (#5056)
fix test_node_request_snapshot_reject_merge (#5056)

* fix test_node_request_snapshot_reject_merge

Signed-off-by: 5kbpers <82ce634e1749ff1c036c2970dd69219ac9501357@pingcap.com>

* add some comments to test_node_request_snapshot_reject_merge

Signed-off-by: 5kbpers <82ce634e1749ff1c036c2970dd69219ac9501357@pingcap.com>

BusyJay/tikv,BusyJay/tikv,pingcap/tikv,c4pt0r/tikv,pingcap/tikv,BusyJay/tikv,BusyJay/tikv