ranger: fix the case which could have duplicate ranges (#24590)#24634

Merged

ti-chi-bot merged 3 commits intopingcap:release-4.0from ti-srebot:release-4.0-aecff1c42e3a

May 14, 2021

+12-4

Commits on May 13, 2021

cherry pick pingcap#24590 to release-4.0

winoros
authored and
ti-srebot
committed

Commits on May 14, 2021