The command ListPopLastPushHead (RPOPLPUSH) is now defined as an inline command instead of bulk after a change in Redis 1.2.1. The old bulk RPOPLPUSH has been preserved and renamed in ListPopLastPushHeadBulk, so that you can override the current server profile if you need the old (and uncorrect) behaviour when connecting to a Redis 1.2.0 instance.

lib/Predis.php

@@ -1262,7 +1262,11 @@ class ListRemove extends \Predis\BulkCommand {
     public function getCommandId() { return 'LREM'; }
 }
 
-class ListPopLastPushHead extends \Predis\BulkCommand {
+class ListPopLastPushHead extends \Predis\InlineCommand {
+    public function getCommandId() { return 'RPOPLPUSH'; }
+}
+
+class ListPopLastPushHeadBulk extends \Predis\BulkCommand {
     public function getCommandId() { return 'RPOPLPUSH'; }
 }