Windows Self-Hosted Test

Here are some steps the worked running on Windows.

1. Install Docker on a Windows host
2. Launch a Powershell.exe session
3. Run the following in power shell to start a container running the nightly toolchain

   docker run --rm --interactive --tty swiftlang/swift:nightly-main-windowsservercore-1809 powershell.exe
   

4. When the container start, clone the "merged" PR to C:\source

   mkdir C:\source
   cd C:\source
   git clone https://github.com/swiftlang/swift-package-manager .
   # Assign the PR ID to a variable
   $PR_ID = "8288"
   git fetch origin pull/$PR_ID/merge:ci_merge_$PR_ID
   git checkout ci_merge_$PR_ID
   

5. Run the CI pipeline script

   python C:\source\Utilities\build-using-self