.version file in PSB artifacts has an incorrect RepositoryCommit

[ViktorHofer]

https://github.com/dotnet/dotnet/blob/b3a6d45a11810606ba46775d7ed6ff6c7feb0fa5/eng/finish-source-only.proj#L179

[MichaelSimons]

[Triage] The current test should be updated to ensure regressions like this are caught.