copr: fix panic when exceeds deadline before polling (#10853)
copr: fix panic when exceeds deadline before polling (#10853)

Signed-off-by: Zhenchi <178a9558f2f6db739d4272cd54221608e811ad26@outlook.com>
BusyJay/tikv,BusyJay/tikv,BusyJay/tikv,BusyJay/tikv