Revert "behaviour change: always populate full series"

This reverts commit cf5fb5b2cf2be80e16bbd6d7ae20b6151ca546ac.

This introduced a bug, revert to do it right.
behaviour change: always populate full series

even for single episodes we now populate the full series structure
without that we can't acces things like the total episode counts and do
proper zero-padding, and other things

this commit reimplements the buggy change from before