Confusing standard output

[John Gourlay]

I’ve noticed that LilyPond 2.19.35 on some valid ly files produces standard 
output meaningless to me. In addition to the standard output saying, 
“Processing”, "Parsing”, etc., it outputs two copies of a long list that starts 
“(list ‘abs-fontsize-markup”. These lists appear if the input ly file contains 
a \header block, and the lists do not appear if the input lacks a \header. Is 
this a feature I don’t understand, or a bug? If it’s a bug, can someone give me 
a pointer that will help me figure out how to fix it? I’m looking for an easy, 
first contribution to LilyPond development, and hoping this might be it.

John Gourlay