Cloning simplenews issue copies sending status

Problem/Motivation

This module is a great module and I would like to use it with simplenews module, to duplicate simplenews issues.
Unfortunately when we use quick_node_clone on a simplenews issue content, all the data from the original node for the field simplenews_isssue is set on the new node;
So, if the original node has already been sent before the duplication, the new node is considered as sent too and can't be send.

Proposed resolution

I propose to remove the data for the field simplenews_issue when duplicated data are set on the new node .
I add patch in this issue.