I think the Oscar upgrade/forking process for forked apps will get
simpler with the new migrations. One probably will be able to just fake
an initial migration, or something like that. But for now, copying
them across as we did before should be a safe bet.

South isn't supported in Django 1.7 and upwards, so we can only skip
them.

I presume filter returns an iterator in Python 3.

Duplicate migration numbers can happen when merging changes from
different branches. This test ensures that we address the issue right
away.

New migrations need to be manually updated to correctly deal with custom
user models. This test fails if this isn't done.