blockchain 单元测试偶发失败

[bysomeone]

--- FAIL: TestBlockChain (0.77s)
chain_test.go:774: testLoadBlockBySequence curheight 11 lastseq 12 Block.Height 12
chain_test.go:815: ErrBlockHashNoMatch

https://github.com/33cn/chain33/runs/4698256447?check_suite_focus=true