Revert "Use atomic create in EtcdHelper.AtomicUpdate"

pkg/tools/etcd_tools.go

@@ -98,11 +98,6 @@ func IsEtcdTestFailed(err error) bool {
 	return isEtcdErrorNum(err, EtcdErrorCodeTestFailed)
 }
 
-// IsEtcdNodeExist returns true iff err is an etcd node aleady exist error.
-func IsEtcdNodeExist(err error) bool {
-	return isEtcdErrorNum(err, EtcdErrorCodeNodeExist)
-}
-
 // IsEtcdWatchStoppedByUser returns true iff err is a client triggered stop.
 func IsEtcdWatchStoppedByUser(err error) bool {
 	return etcd.ErrWatchStoppedByUser == err
@@ -258,20 +253,15 @@ func (h *EtcdHelper) AtomicUpdate(key string, ptrToType interface{}, tryUpdate E
 			return err
 		}
 
+		// First time this key has been used, just set.
+		if index == 0 {
+			return h.SetObj(key, ret)
+		}
+
 		data, err := h.Encoding.Encode(ret)
 		if err != nil {
 			return err
 		}
-
-		// First time this key has been used, try creating new value.
-		if index == 0 {
-			_, err = h.Client.Create(key, string(data), 0)
-			if IsEtcdNodeExist(err) {
-				continue
-			}
-			return err
-		}
-
 		_, err = h.Client.CompareAndSwap(key, string(data), 0, origBody, index)
 		if IsEtcdTestFailed(err) {
 			continue