title: Accessing the build revision number in Powershell script during TFS build
body: <p>I can get the build number from IBuildDetail.BuildNumber but this is taken from the build definition and there fore might not include the revision number $(Rev:.r) or it might not be at the end.</p>
  
  <p>So I would like to get this number without having to parse it from the build number.  Is this property available any where during the build?</p>