Race condition in sshd.

[Foxboron]

Describe the bug
When using x/crypto/ssh to connect with sshd there is no output from the session with CombinedOutput. And manually using OpenSSH to connect to sshd sometimes doesn't give any output back.

I suspect there is a race condition somewhere but I have not managed to figure out where.

To Reproduce
Start sshd and use x/crypto/ssh to open a session and use CombinedOutput. It will fail with EOF.

Expected behavior
The command should return something.

Additional context
N/A

[Foxboron]

My running theory is that using e.Process.Wait instead of e.Wait() is the main issue, as we are exiting the before everything is written to stdout/stdin/stderr.

I'm at a loss on how we should properly fix this, but I'm wondering if just execing with CombinedOutput and then io.Copy it to c would be a better solution? Currently it seems e.Wait() chokes on the channel we are giving it.

[Foxboron]

cc @bluecmd :)

[binjip978]

I had similar issue with EOF when I was trying to write test for this command: #2963 and initially I was trying combinedOutput or Output and got only EOF. I tested sshd command with other ssh clients and saw no issues, but what seemed to work is to pipe Stdout and then I got an output. But still I have linux box where this test fails reliably :)