I don't think that's required, since we're not importing galsim here.  Just doing simple python stuff.  So any version of python should work.  

This basically just runs diff for me, but then if there is a difference, it gives more information, so I can tell whether the difference is significant or just rounding errors.  While working on this branch, there were some 1.e-11 kinds of differences because the new syntax switches the order of pixel convolution and pixel scale dilation (mathematically equivalent, but numerically different), so it was helpful to know when not to worry about them.