Completely fails due to authentication problem: API changes, I think!

[GoogleCodeExporter]

Last ran a backup on May 4. Just tried to run one today (May 29), and it fails 
immediately, with this error:

GDataRequestException: Execution of authentication request returned unexpected 
result: 404.

Anyone else getting this?

I'm pretty sure that it's due to some changes in how the API/auth. is working; 
a quick DuckDuckGo search turned these up:

https://code.google.com/p/google-gdata/issues/detail?id=716

http://stackoverflow.com/questions/30469058/google-gdata-client-gdatarequestexce
ption-authentication-suddenly-fails-in-old

I'm assuming something can be done to fix GDocBackup; if anyone with experience 
of using these APIs has time to poke around in the source, that'd be great.

I can have a look, but not for a couple of weeks. And even then, I fear the fix 
won't be completely trivial, so I might not be able to help.

Unfortunately, it seems GDocBackup is completely unusable until then! If anyone 
finds a workaround, please let us know. :)

Thanks.

Original issue reported on code.google.com by [email protected] on 29 May 2015 at 6:27