`running_aspnet_compiler_under_dotNet35_should_pass.ps1` fails because they use Exec to run each task [here](https://github.com/psake/psake/commit/ee9dfef0#diff-030ecb247f5a332a6ccd63e8b7924cfeR90).

The spec passes if you [reset the var](https://gist.github.com/vorou/8103225), but it doesn't look clear. I wonder should we combine retrying logic with lastexitcode checking at all.