Doesn't work:
anderson $ ssh -A root@remotehost
root[remotehost] $ ssh -T git@github.com
Does work:
anderson $ ssh -A nonroot@remotehost
root[remotehost] $ ssh -T git@github.com
So for some reason root is being blocked from forwarding, which makes no sense to me since forwarding only exposes the original client machine, not the remote.
So it's not OS X... it's Ubuntu. ;-)
Thanks anyways. Now I have to figure out how to convince Ansible to configure things via sudo instead (which it will do, but only for an entire playbook at a time, not just a single task).