tikv: fix infinite panic when GRPC transportReader is broken (#18437)#18562

Merged

coocood merged 3 commits intopingcap:release-4.0from ti-srebot:release-4.0-ca41972fbac0

Jul 15, 2020

+15-4

Commits on Jul 14, 2020

cherry pick pingcap#18437 to release-4.0

lysu
authored and
ti-srebot
committed

Commits on Jul 15, 2020