My ssh agent admitted failure to sign a key!

This morning I decided to push some commits to a git repository at Assembla.com. Unfortunately I forgot my pass phrase for the specific key I generated and ended up with:

Agent admitted failure to sign using the key.
Permission denied (publickey,keyboard-interactive).
fatal: The remote end hung up unexpectedly

Which is fine, so I just create a new ssh key using the same name and it should work… Sadly it didn’t because some ssh-agent remembered that I don’t remember the pass phrase, so it reported that to the server. Then the assembla server drops the connection. After some searching on the internet I learned that you should use ssh-add [filename] to add the key to my ssh key chain. That worked fine and I can push my commits¬†again.