Fix new commondata filters
Created by: Radonirinaunimi
This does not attempt to polish the new commondata implementation, but simply to make sure that the filters run properly. The main purpose of this PR is to make https://github.com/NNPDF/nnpdf/pull/2099 works.
This has a minimal conflict with https://github.com/NNPDF/nnpdf/pull/2056, but that's something that can be solved easily.