Thanks to a tip form Kevin Dillon, a work-around to the problem with new Google Forms has been identified! Legacy Google Forms are still available IF you start creating the form by opening a SpreadSheet first. Once the spreadsheet is open, select “Create a legacy Form” from the “Tools” menu. The form editor and published URL will be the same as those that had worked prior to the Google Forms update.
I have spent some time comparing low level WP_Http results against wget results and have come to the conclusion that Google Cookies aren’t being passed through the series of redirect which happens when viewing a Google Form with the new URL scheme.
Unfortunately I am not sure what to do about it yet. The usually very helpful WordPress Hackers mailing list is surprising quiet right now. I am trying to figure out if I can “remember” cookies and pass them along each time a redirect happens. I am reasonably confident that is what is needed however making it happen within the WordPress context is another story!