Code review comment for lp:~adiroiban/launchpad/bug-531261

They fail here too, and the reason why they're failing is that on this
branch I asked you to move the active attribute from SeriesMixin to
DistroSeries because it seemed to be used only there. That was wrong --
ProductSeries inherits from SeriesMixin and, as you noticed, we have
code that rely on ProductSeries.attribute.

I think the correct fix here is to move the 'active' property back to
SeriesMixin. After you do that you'll have to update one of the
webservice tests for ProductSeries because its webservice representation
will now contain an extra 'active' field.