Capistrano and Github (Private) Repositories

[ParkinT]

I wonder if anyone has

1. Also noticed this problem
2. Has a solution for my dilema

Apparently, something has changed wrt Github and it affects the ability to use Capistrano; specifically it affects the ability to CLONE repositories on a remote server.

I have written a Gist with details, but here is the 'gist' of my problem:

I am new to Capistrano and have one app that is working as expected. This was instantiated months ago and the repo in Github is private.
When I now try to setup ANY new instances (RoR projects) I encounter a problem. That is, during the "clone" operation in Capistrano (using agent_forward and SSH keys that work from my local machine) the "ERROR: Repository not found" error appears. But, as I have verified through testing, ONLY if I use a Github repository that is set to Private.
Furthermore, if I temporarily change the Public/Private status of any of my repositories I can get Capistrano to operate correctly.

I am not pointing to Capistrano as the cause of this problem. Based on the symptoms it appears to be something odd with Github (or git).

I would appreciate any insight. Post it here and/or on the Gist I created.

Thanks.

[ParkinT]

It appears I am [somehow] alone in experiencing this problem.
Deductive reasoning would indicate an issue either with Github or with Capistrano.
Since I am using the "agent forward" capability I was suspicious of my SSH key.
When Capistrano issues a git clone command - on my behalf - from the server the "Repository not found" is returned. But if I, from an SSH session on the server, issue the identical command it works!

If you have some experience with Capistrano (any experience would be more than I have) can you suggest a 'workflow' and 'configuration' that I might try as a known, good default?

[ParkinT]

Here is a Gist with details (and updates) to this issue.
In case someone else is experiencing a similar problem this may be helpful.

If anyone has important data to add to this, please comment on the Gist (or PM me).