Cloning from new host via ssh causes spurious error rather than prompting for confirmation and succeeding

[ctcjab]

Description

Using jupyterlab-git to clone a repo over ssh when the server is not yet in ~/.ssh/known_hosts causes the following "failed to clone" error:

Clicking "Show" produces the following somewhat spurious error:

The failure is due to jupyterlab-git not handling the case when the host key is not yet in ~/.ssh/known_hosts, so the error message should list that as a potential cause, in addition to the user not having access rights or the repo not existing.

Better yet, jupyterlab-git should handle this case and provide a graphical UI for the user to confirm, similar to how the command line git client exposes this via text UI:

$ git clone ssh://git@bitbucket.example.com:7999/foo/bar.git
Cloning into 'bar'...
The authenticity of host '[bitbucket.example.com]:7999 ([X.Y.Z.W]:7999)' can't be established.
RSA key fingerprint is SHA256:<fingerprint>.
This key is not known by any other names
Are you sure you want to continue connecting (yes/no/[fingerprint])? yes
Warning: Permanently added '[bitbucket.example.com]:7999' (RSA) to the list of known hosts.
remote: Enumerating objects: 18, done.
remote: Counting objects: 100% (18/18), done.
remote: Compressing objects: 100% (17/17), done.
remote: Total 18 (delta 0), reused 0 (delta 0), pack-reused 0
Receiving objects: 100% (18/18), 560.80 KiB | 24.38 MiB/s, done.

This way the user doesn't have to switch away from jupyterlab-git to the terminal in order to clone the repo, which some less technical users may be unable to do by themselves.

Reproduce

1. Click "Clone a Repository"
2. Paste the URL of a git repo that is hosted via SSH and whose host's fingerprint does not appear in ~/.ssh/known_hosts
3. Click "Clone"

Expected behavior

Provide a user-friendly confirmation ("It looks like this is the first time you're cloning from this server via SSH, do you want to continue?" (perhaps with a "details" button the user can click to reveal more technical details, including the host key fingerprint). Once the user confirms, the confirmation is passed through to ssh so it can update ~/.ssh/known_hosts, and from that point forward the user can successfully use jupyterlab-git to clone from this host via ssh without needing to confirm again.

Context

• Python package version:

• Extension version: 0.50.1

• Git version: 2.34.1

• Operating System and its version: Ubuntu 22.04 LTS

Command Line Output

Paste the output from your command line running `jupyter lab` here, use `--debug` if possible. N/A

Web Browser Output

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