etcdctl: sync before running member subcommands

etcdctl/command/member_commands.go

@@ -48,6 +48,11 @@ func mustNewMembersAPI(c *cli.Context) client.MembersAPI {
 		os.Exit(1)
 	}
 
+	if err := hc.Sync(); err != nil {
+		fmt.Fprintln(os.Stderr, err.Error())
+		os.Exit(1)
+	}
+
 	return client.NewMembersAPI(hc, client.DefaultRequestTimeout)
 }