integration: fix govet error in Go tip
integration: fix govet error in Go tip

Signed-off-by: Gyuho Lee <3454051ee3341eb69bdf6fca40899cdad4d86496@gmail.com>

rnaveiras/etcd,bdarnell/etcd,rnaveiras/etcd,mqliang/etcd,gyuho/etcd,xiang90/etcd,mkumatag/etcd,etcd-io/etcd,heyitsanthony/etcd,sinsharat/etcd,ajityagaty/etcd,glevand/coreos--etcd,joshix/etcd,glevand/coreos--etcd,sebrandon1/etcd,fanminshi/etcd,whuwxl/etcd,fanminshi/etcd,whuwxl/etcd,dannysauer/etcd,joshix/etcd,cockroachdb/etcd,li-ang/etcd,dannysauer/etcd,vimalk78/etcd,mqliang/etcd,sinsharat/etcd,coreos/etcd,etcd-io/etcd,mkumatag/etcd,cockroachdb/etcd,mkumatag/etcd,mqliang/etcd,bdarnell/etcd,li-ang/etcd,vimalk78/etcd,heyitsanthony/etcd,sebrandon1/etcd,ajityagaty/etcd,gyuho/etcd,lorneli/etcd,rnaveiras/etcd,etcd-io/etcd,lorneli/etcd,ajityagaty/etcd,xiang90/etcd,coreos/etcd