Fix for SSH remoting when banner is enabled on SSHD endpoint

[PaulHigin]

PR Summary

This is a fix for Issue #15759.

PR Context

The SSH transport currently terminates a connection attempt if SSH writes any error to stdErr stream, essentially making any SSH error a terminating error. However, data stdErr is unreliable for this since it can contain warnings, the endpoint banner text, and probably other non-error related information, and this can cause an SSH connection to fail unnecessarily.

Fix is to just remove this code and only write the stdErr data to the terminal. A user can terminate an SSH connection in one of two ways;

• Typing Ctrl+C in an interactive session
• Using the -ConnectingTimeout parameter in the New-PSSession, Invoke-Command, Enter-PSSession cmdlets

PR Checklist

• PR has a meaningful title
  • Use the present tense and imperative mood when describing your changes
• Summarized changes
• Make sure all .h, .cpp, .cs, .ps1 and .psm1 files have the correct copyright header
• This PR is ready to merge and is not Work in Progress.
  • If the PR is work in progress, please add the prefix WIP: or [ WIP ] to the beginning of the title (the WIP bot will keep its status check at Pending while the prefix is present) and remove the prefix when the PR is ready.
• Breaking changes
  • None
  • OR
  • Experimental feature(s) needed
    • Experimental feature name(s): PSRemotingSSHTransportErrorHandling
• User-facing changes
  • Not Applicable
  • OR
  • Documentation needed
    • Issue filed:
• Testing - New and feature
  • N/A or can only be tested interactively
  • OR
  • Make sure you've added a new test if existing tests do not effectively test the code changed
• Tooling
  • I have considered the user experience from a tooling perspective and don't believe tooling will be impacted.
  • OR
  • I have considered the user experience from a tooling perspective and opened an issue in the relevant tool repository. This may include:
    • Impact on PowerShell Editor Services which is used in the PowerShell extension for VSCode
      (which runs in a different PS Host).
      • Issue filed:
    • Impact on Completions (both in the console and in editors) - one of PowerShell's most powerful features.
      • Issue filed:
    • Impact on PSScriptAnalyzer (which provides linting & formatting in the editor extensions).
      • Issue filed:
    • Impact on EditorSyntax (which provides syntax highlighting with in VSCode, GitHub, and many other editors).
      • Issue filed:

[ghost]

Open PRs should not be assigned to milestone, so they are not assigned to the wrong milestone after they are merged. For backport consideration, use a backport label.

[PaulHigin]

@daxian-dbw Is there anything preventing this from being merged into vNext branch?

[ghost]

Open PRs should not be assigned to milestone, so they are not assigned to the wrong milestone after they are merged. For backport consideration, use a backport label.

[daxian-dbw]

@PaulHigin You forgot to move this to "Ready for review", so I didn't know this is ready to be merged.
I will mark it as ready and merge it.

[daxian-dbw]

Oh, there are conflicts. Can you please rebase your changes to resolve the conflicts?

[PaulHigin]

I checked the This PR is ready to merge and is not Work in Progress.' in the check list. I didn't see a Ready for Review. Also I disagree with adding a comma to the end of the experimental list.

[daxian-dbw]

I didn't see a Ready for Review.

Ilya marked your PR as draft when he left his comment:

I marked it "ready for review" 2 days ago when saw your comment:

"Ready for review" button is at the right corner of the CI part of a draft PR:

Also I disagree with adding a comma to the end of the experimental list.

It has been this way for previous changes to this list, for example, PSNativeCommandErrorActionPreferenceFeatureName, PSAnsiRenderingFileInfo, and PSLoadAssemblyFromNativeCode. It adds a little convenience when adding a new item at the end of the list.

[PaulHigin]

Just because it has been that way before doesn't mean I have to agree to it :)

[daxian-dbw]

Of course :) Just wanted to clarify why I made that minor change.

[ghost]

🎉v7.3.0-preview.1 has been released which incorporates this pull request.:tada:

Handy links:

• Release Notes