Steps to reproduce:

1. Enable password authentication on ssh server 
2.  17708:20200211:161135.672 ssh_run() supported authentication methods:'publickey,password'
3. ssh_run() works fine
4. Disable password auth on ssh server (pubkey only)
5. 17118:20200211:154935.628 ssh_run() supported authentication methods:'publickey'
   17118:20200211:154935.631 End of ssh_run():NOTSUPPORTED
   17118:20200211:154935.631 Item [www1.stride.ws:ssh.run[apache procs]] error: Public key authentication failed: Invalid signature for supplied public key, or bad username/public key combination

Result:
Can't login with pubkey when ONLY pubkey allowed (auth_pw & 4)

Can login with pubkey when pubkey & password allowed (auth_pw & 1) - even though no password set and using pubkey auth

Expected:
Can login with pubkey when ONLY pubkey allowed (auth_pw & 4)

Can login with pubkey when pubkey & password allowed (auth_pw & 1) - even though no password set and using pubkey auth