Comment 89 for bug 201786

Summary of problem (for me):

* ssh host fails with "ssh Agent admitted failure"
* SSH_AUTH_SOCK= ssh host works just fine
* Conclusion: gnome-keyring can't deal with complex keys

WORKAROUND:

mv $SSH_AUTH_SOCK $SSH_AUTH_SOCK.broken
ssh-agent -a $SSH_AUTH_SOCK

This is a new instance of ssh-agent, so it won't have any keys in it (despite what seahorse says, since that's tied to the .broken agent). You'll have to add them via ssh-add.