etcdmain: handle StopNotify when ErrStopped aborted publish

Fix https://github.com/coreos/etcd/issues/7512.

If a server starts and aborts due to config error,
it is possible to get stuck in ReadyNotify waits.
This adds select case to get notified on stop channel.

Signed-off-by: Gyu-Ho Lee <gyuhox@gmail.com>

etcdmain/etcd.go

@@ -189,7 +189,10 @@ func startEtcd(cfg *embed.Config) (<-chan struct{}, <-chan error, error) {
 		return nil, nil, err
 	}
 	osutil.RegisterInterruptHandler(e.Server.Stop)
-	<-e.Server.ReadyNotify() // wait for e.Server to join the cluster
+	select {
+	case <-e.Server.ReadyNotify(): // wait for e.Server to join the cluster
+	case <-e.Server.StopNotify(): // publish aborted from 'ErrStopped'
+	}
 	return e.Server.StopNotify(), e.Err(), nil
 }