Exception raised when trying to sort a "Variant" sequence in Python 3

While migrating some of our code to Python 3, I noticed that a few of our unit tests are breaking:

> TypeError("'<' not supported between instances of 'Variant' and 'Variant'")

So while we maybe should not have tried to sort `Variant` sequences, it was certainly not raising an exception with Python 2.7, shouldn't it be possible to sort them by using the family and version of the underlying `FileSystemVariantResource` ?

Cheers,

Thomas

Start by reproducing the failing unit tests under Python 3 and tracing how Variant sequences are sorted relative to FileSystemVariantResource. Check whether family and version provide the intended ordering, then consider the issue done when sorting no longer raises the reported TypeError and the affected tests pass.

Written by the indexing model from the issue text.