etcdserver: fix append object to a new allocated sized slice
etcdserver: fix append object to a new allocated sized slice

mkumatag/etcd,rnaveiras/etcd,cockroachdb/etcd,ajityagaty/etcd,cockroachdb/etcd,coreos/etcd,ajityagaty/etcd,etcd-io/etcd,mqliang/etcd,mqliang/etcd,coreos/etcd,rnaveiras/etcd,mkumatag/etcd,dannysauer/etcd,etcd-io/etcd,rnaveiras/etcd,li-ang/etcd,mqliang/etcd,gyuho/etcd,dannysauer/etcd,mkumatag/etcd,ajityagaty/etcd,li-ang/etcd,gyuho/etcd,etcd-io/etcd