Fix Del command case.

cluster.go

@@ -235,6 +235,7 @@ func (c *ClusterClient) slotClosestNode(slot int) (*clusterNode, error) {
 func (c *ClusterClient) cmdSlotAndNode(cmd Cmder) (int, *clusterNode, error) {
 	cmdInfo := c.cmdInfo(cmd.arg(0))
 	if cmdInfo == nil {
+		internal.Logf("info for cmd=%s not found", cmd.arg(0))
 		node, err := c.randomNode()
 		return 0, node, err
 	}

commands.go

@@ -82,7 +82,7 @@ func (c *statefulCmdable) Select(index int) *StatusCmd {
 
 func (c *cmdable) Del(keys ...string) *IntCmd {
 	args := make([]interface{}, 1+len(keys))
-	args[0] = "DEL"
+	args[0] = "del"
 	for i, key := range keys {
 		args[1+i] = key
 	}
@@ -550,7 +550,7 @@ func (c *cmdable) Set(key string, value interface{}, expiration time.Duration) *
 
 func (c *cmdable) SetBit(key string, offset int64, value int) *IntCmd {
 	cmd := NewIntCmd(
-		"SETBIT",
+		"setbit",
 		key,
 		offset,
 		value,

ring.go

@@ -169,6 +169,7 @@ func (c *Ring) cmdInfo(name string) *CommandInfo {
 func (c *Ring) cmdFirstKey(cmd Cmder) string {
 	cmdInfo := c.cmdInfo(cmd.arg(0))
 	if cmdInfo == nil {
+		internal.Logf("info for cmd=%s not found", cmd.arg(0))
 		return ""
 	}
 	return cmd.arg(int(cmdInfo.FirstKeyPos))