Get-BranchName fails inside Psake

[Iristyle]

redirecting 2> $null seems to cause some issues

We want to proceed if not a Git repo, and try to see if it's an HG repo.

However, calling Get-BranchName in a build totally kills Psake :(

[Iristyle]

http://stackoverflow.com/questions/10666101/powershell-lastexitcode-0-but-false-redirecting-stderr-to-stdout-gives-nat