It seems matplotlib includes fonts without license. And that the generally available license for said fonts is not really free (limited to non-commercial use).

Bug #6976 references the LyX project and their file ReadmeBaKoMa4LyX as proof of origin for some fonts shipped with matplotlib. That file references web page http://www.ctan.org/tex-archive/systems/win32/bakoma/ which describes the BaKoMa fonts as Shareware. At other places - e.g. http://www.math.utah.edu/~beebe/fonts/bakoma.html - the BaKoMa fonts are described as "free" but only for non-commercial use.

I recommend to add a file in same folder as the BaKoMa(-derived) fonts where you clarify its origin and license - including quoting verbatim the licensing terms as they were given to you from Basil - directly or possibly via redistribution, but not hearsay.

In my understanding, If project A receives the fonts and a license for using them, but then redistributes the fonts without the license, then project B is not licensed to use the fonts!

You need not agree with my understanding of licensing - I am not here to point fingers at others. Issue here is that even if your interpretation of licensing requirements are more relaxed, then others - like Debian that I am part of - may impose a more strict interpretation and therefore need the details you possible feel are unneeded for your legal coverage.