Minor changes to Python test harness to allow it to be used on Windows.  Closes #4366

We have some tests for the Raven framework that we want to run on Windows.  There are a couple of small issues that prevent it from running out of the box with the Windows Python distribution.
How long does this take?  This is in a performance sensitive region.  If we're going to do this (which we shouldn't) then we should do it once... up front somewhere and store the result.