raft: add more assertions for dueling candidates test case
raft: add more assertions for dueling candidates test case

OyTao/etcd_learning,sofuture/etcd,plasticbox/etcd,linuxcer/etcd,gyuho/etcd,ktateish/etcd,wantonsolutions/dinv-etcd,whuwxl/etcd,chipironcin/etcd,purpleidea/etcd,rchicoli/etcd,ravigadde/etcd,sebrandon1/etcd,mqliang/etcd,StorReduce/etcd,visheshnp/etcd,bluebreezecf/etcd,glycerine/etcd,fanminshi/etcd,westhood/etcd,coreos/etcd,ajityagaty/etcd,OyTao/etcd_learning,a-robinson/etcd,yudai/etcd,zaphod-concur/etcd,bdarnell/etcd,YuleiXiao/etcd,dnaeon/etcd,qqsun8819/etcd,mkumatag/etcd,bdarnell/etcd,endocode/etcd,rchicoli/etcd,glycerine/etcd,dnaeon/etcd,mickep76/etcd,nekto0n/etcd,cockroachdb/etcd,akauppi/etcd,wantonsolutions/dinv-etcd,YuleiXiao/etcd,li-ang/etcd,etcd-io/etcd,hongchaodeng/etcd,sinsharat/etcd,a-robinson/etcd,dannysauer/etcd,yudai/etcd,heyitsanthony/etcd,heyitsanthony/etcd,handsomesun/etcd,sebrandon1/etcd,mqliang/etcd,sinsharat/etcd,linuxcer/etcd,etcd-io/etcd,rnaveiras/etcd,vimalk78/etcd,hongchaodeng/etcd,jonboulle/etcd,luxas/etcd,StorReduce/etcd,whuwxl/etcd,etcd-io/etcd,plasticbox/etcd,nekto0n/etcd,handsomesun/etcd,luxas/etcd,gyuho/etcd,armstrongli/etcd,ktateish/etcd,westhood/etcd,lorneli/etcd,akauppi/etcd,jlamillan/etcd,mqliang/etcd,vimalk78/etcd,bluebreezecf/etcd,lorneli/etcd,lumjjb/etcd,CrazyJvm/etcd,CrazyJvm/etcd,coreos/etcd,sofuture/etcd,chipironcin/etcd,swingbach/etcd,li-ang/etcd,fanminshi/etcd,jlamillan/etcd,purpleidea/etcd,tguangch/etcd,ajityagaty/etcd,xiang90/etcd,endocode/etcd,ravigadde/etcd,joshix/etcd,rnaveiras/etcd,insequent/etcd,lumjjb/etcd,glevand/coreos--etcd,dannysauer/etcd,glevand/coreos--etcd,visheshnp/etcd,zaphod-concur/etcd,armstrongli/etcd,xiang90/etcd,mickep76/etcd,swingbach/etcd,qqsun8819/etcd,mkumatag/etcd,wantonsolutions/dinv-etcd,jonboulle/etcd,mkumatag/etcd,rnaveiras/etcd,ajityagaty/etcd,tguangch/etcd,joshix/etcd,insequent/etcd,cockroachdb/etcd