etcdctl/ctlv3: etcd v3.4 makes ETCDCTL_API=3 by default

etcdctl/main.go

@@ -31,13 +31,13 @@ func main() {
 	apiv := os.Getenv(apiEnv)
 	// unset apiEnv to avoid side-effect for future env and flag parsing.
 	os.Unsetenv(apiEnv)
-	if len(apiv) == 0 || apiv == "2" {
-		ctlv2.Start(apiv)
+	if len(apiv) == 0 || apiv == "3" {
+		ctlv3.Start(apiv)
 		return
 	}
 
-	if apiv == "3" {
-		ctlv3.Start()
+	if apiv == "2" {
+		ctlv2.Start()
 		return
 	}