raft: bug fix (#12123)
raft: bug fix (#12123)

we need to test the case when configuration set is changed, but there is typo.

None

Signed-off-by: accelsao <1e0d9905a2fd99b275484dfbc8051d4d4408a530@gmail.com>
mkumatag/etcd,rnaveiras/etcd,ajityagaty/etcd,dannysauer/etcd,etcd-io/etcd,gyuho/etcd,gyuho/etcd,etcd-io/etcd,etcd-io/etcd,rnaveiras/etcd,mkumatag/etcd,rnaveiras/etcd,mkumatag/etcd,li-ang/etcd,li-ang/etcd,ajityagaty/etcd,coreos/etcd,ajityagaty/etcd,mqliang/etcd,mqliang/etcd,mqliang/etcd,dannysauer/etcd,coreos/etcd