ssh-agent does not accept all forwarded RSA keys on later versions.

[Matt Schepers]

Hello,

I've got a problem with newer versions of ssh-agent not accepting all keys
being forwarded to them.

Example:
LOCAL-WORKSTATION
ssh-add -l
4096 SHA256:HFSzrozPapudofYJi8QvXQdA1/vNpFc2iPWH8CGVsEg (none) (RSA)
2048 SHA256:lbjpmHAYtUO+zaLaKvWVxGNYkXRkOumcoOpLdRSVX/U
/home/matt/.ssh/id_rsa_embedded (RSA)
ssh -V
OpenSSH_7.6p1 Ubuntu-4ubuntu0.3, OpenSSL 1.0.2n  7 Dec 2017

BROKEN-REMOTE
ssh -A brokenHost
ssh-add -l
2048 SHA256:lbjpmHAYtUO+zaLaKvWVxGNYkXRkOumcoOpLdRSVX/U
/home/matt/.ssh/id_rsa_embedded (RSA)
ssh -V
OpenSSH_8.2p1 Ubuntu-4ubuntu0.1, OpenSSL 1.1.1f  31 Mar 2020
Here only one key gets forwarded when there should be two. That's what the
problem is.

WORKING-REMOTE
ssh -A workingHost
ssh-add -l
4096 SHA256:HFSzrozPapudofYJi8QvXQdA1/vNpFc2iPWH8CGVsEg (none) (RSA)
2048 SHA256:lbjpmHAYtUO+zaLaKvWVxGNYkXRkOumcoOpLdRSVX/U
/home/matt/.ssh/id_rsa_embedded (RSA)
ssh -V
OpenSSH_7.6p1 Ubuntu-4ubuntu0.3, OpenSSL 1.0.2n  7 Dec 2017


So the problem appears to be that the newer version is not accepting all of
the forwarded keys. I'd like to troubleshoot this and/or file a bug report.
Can you guys point me in the right direction?


Regards
Matt