Cluster: better comment for clusterSendFailoverAuthIfNeeded() epoch test.
Cluster: better comment for clusterSendFailoverAuthIfNeeded() epoch test.

slfs007/mk-redis,MSOpenTech/redis,xuzhezhaozhao/redis_reading,jxwr/redis,MSOpenTech/redis,HunanTV/redis,louisliangjun/redis,ksarch-saas/redis,darksideofthemoo/redis-histogram,splitice/redis,HunanTV/redis,louisliangjun/redis,xuzhezhaozhao/redis_reading,ttuna/msot-redis,splitice/redis,HunanTV/redis,splitice/redis,slfs007/mk-redis,spearhead-ea/redis,ttuna/msot-redis,himoca/redis,himoca/redis,ramonsnir/redis,MSOpenTech/redis,darksideofthemoo/redis-histogram,maodeyi/redis_lua,ttuna/msot-redis,slfs007/mk-redis,himoca/redis,jxwr/redis,MSOpenTech/redis,ksarch-saas/redis,MSOpenTech/redis,ksarch-saas/redis,maodeyi/redis_lua,ramonsnir/redis,xuzhezhaozhao/redis_reading,splitice/redis,darksideofthemoo/redis-histogram,darksideofthemoo/redis-histogram,ttuna/msot-redis,ramonsnir/redis,xuzhezhaozhao/redis_reading,spearhead-ea/redis,HunanTV/redis,louisliangjun/redis,spearhead-ea/redis,ksarch-saas/redis,ttuna/msot-redis,jxwr/redis,louisliangjun/redis,maodeyi/redis_lua