It had already been SPRed. It has to do with the XPages core librairie. Fortunately, we know how to fix, by changing the way dojo emits an xhr to the server, using a hidden iframe and a form post.
More than that, it had been partially implemented in the extlib, within the dialog. You can set a dojo attribute called iframePost, and it temporarily switches dojo xhr.
You can probably do the same in your partial refresh, before we provide a better fix. Look at Dialog.js in the extlib to see how it set/reset the xhr method.