colab ssh doesn't work if identity isn't added to ssh-agent #233

$ ssh-add ~/.ssh/id_ed25519
Enter passphrase for /home/once/.ssh/id_ed25519: 
Identity added: /home/once/.ssh/id_ed25519 (once@once)

$ uv run colab ssh
[colab] Using unique session 'a9683e'.
/content# exit
logout

$ ssh-agent -k; eval "$(ssh-agent -s)"

$ uv run colab ssh
[colab] Using unique session 'a9683e'.
root@colab-runtime: Permission denied (publickey).

$ uv run colab ssh -i ~/.ssh/id_ed25519.pub
[colab] Using unique session 'a9683e'.
Enter passphrase for key '/home/once/.ssh/id_ed25519': 
/content# 

$ uv run colab ssh -i ~/.ssh/id_ed25519
[colab] Using unique session 'a9683e'.
[colab] failed to derive public key from /home/once/.ssh/id_ed25519: Command '['ssh-keygen', '-y', '-f', '/home/once/.ssh/id_ed25519']' returned non-zero exit status 255.