Issue with installing Ruby on blacksmith.sh Windows runners

[jbaiza]

Ensure the following before filing this issue

• I verified it reproduces with the latest version with - uses: ruby/setup-ruby@v1 (see Versioning policy)

• I tried to reproduce the issue locally by following the workflow steps (including all commands done by ruby/setup-ruby, except for Downloading Ruby & Extracting Ruby),
  and it did not reproduce locally (if it does reproduce locally, it's not a ruby/setup-ruby issue)

Are you running on a GitHub-hosted runner or a self-hosted runner?

self-hosted runner

Link to the failed workflow job (must be a public workflow job, so the necessary information is available)

Any other notes?

We recently tried to switch our action runners from GitHub to blacksmith.sh.
When running on the Windows runner, we faced two issues with Ruby installation:

1. "Windows Server 2025 Standard Evaluation" wasn't recognized as a valid Windows version with the error:

Error: Could not find Windows version

This issue was fixed by changing the Windows version check to:

const match = version.match(/^Windows(?: Server)? (\d+) (?:Standard|Datacenter|Enterprise)/)

2. Bundler wasn't able to install gems due to an issue with finding the HOME directory:

C:\WINDOWS\system32\cmd.exe /D /S /C "C:\jruby-9.4.13.0\bin\bundle.bat install --jobs 8"
`null` is not a directory.
Bundler will use `C:/runner/_work/_temp/bundler20260302-5764-vyhqc85764' as your home directory temporarily.

As the HOME directory wasn't found, preconfigured SSH keys weren't used to fetch private repositories.
This issue was fixed by setting the HOME directory from OS information, not combining environment variables that weren't set on those runners:

core.exportVariable('HOME', os.homedir())

[eregon]

Fixed in #883 and released