Breaking changes of ForwardAgent path parsing

Hi, update to V8.9.1.0p1-Beta breaks backward compatibility of parsing the ForwardAgent path.

• On V8.6.0.0p1-Beta:

C:\Users\buglloc
λ C:\Users\buglloc\Downloads\V8.6.0.0p1-Beta\ssh.exe -V
OpenSSH_for_Windows_8.6p1, LibreSSL 3.3.3

C:\Users\buglloc
λ C:\Users\buglloc\Downloads\V8.6.0.0p1-Beta\ssh.exe "-oForwardAgent=\\.\pipe\openssh-ssh-agent" github.com
buglloc@github.com: Permission denied (publickey).

C:\Users\buglloc
λ C:\Users\buglloc\Downloads\V8.6.0.0p1-Beta\ssh.exe "-oForwardAgent=\\\\.\pipe\openssh-ssh-agent" github.com
Cannot forward agent socket path "\\\\\\\\.\\pipe\\openssh-ssh-agent": Unknown error
buglloc@github.com: Permission denied (publickey).

• On V8.9.1.0p1-Beta :

C:\Users\buglloc
λ C:\Users\buglloc\Downloads\V8.9.1.0p1-Beta\ssh.exe -V
OpenSSH_for_Windows_8.9p1, LibreSSL 3.4.3

C:\Users\buglloc
λ C:\Users\buglloc\Downloads\V8.9.1.0p1-Beta\ssh.exe "-oForwardAgent=\\.\pipe\openssh-ssh-agent" github.com
Cannot forward agent socket path "\\.\\pipe\\openssh-ssh-agent": No such file or directory
buglloc@github.com: Permission denied (publickey).

C:\Users\buglloc
λ C:\Users\buglloc\Downloads\V8.9.1.0p1-Beta\ssh.exe "-oForwardAgent=\\\\.\pipe\openssh-ssh-agent" github.com
buglloc@github.com: Permission denied (publickey).

Which path should I use to be compatible with both (and future) versions? May I use //./pipe/<pipe_name> for example?

Start by tracing the ForwardAgent path parsing behavior in the V8.6.0.0p1-Beta and V8.9.1.0p1-Beta versions described in the report. Determine which path form remains compatible with both versions and future versions, then verify the result using the Windows pipe examples and error messages provided.