Handle reading '0' response in bytes[0] response

Author: mythz

src/ServiceStack.Redis/Pipeline/QueuedRedisOperation.cs

@@ -104,6 +104,9 @@ public void ProcessResult()
                 else if (BytesReadCommand != null)
                 {
                     var result = BytesReadCommand();
+                    if (result != null && result.Length == 0)
+                        result = null;
+
                     if (OnSuccessBytesCallback != null)
                     {
                         OnSuccessBytesCallback(result);