Assertion failure in page-breaking.cc

[Thomas Morley]

The following code:

\version "2.19.54"

\header { title = "Überschrift" }
\score { \new Staff { \repeat unfold 15 { a'2 a'2 } } }
\score { \new Devnull { } \header { piece = "Stück" } }

returns:

lilypond: /home/hermann/lilypond-git/lily/page-breaking.cc:1040: void
Page_breaking::line_divisions_rec(vsize, const Line_division&, const
Line_division&, Page_breaking::Line_division*): Assertion `my_index ==
0' failed.
Aborted (core dumped)


Remark:
- Intended is to print headers with a custom-bookTitleMarkup (not in
the above minimal) for all scores, even for scores without actual
printed music.
- Very small changes to the minimal above will make it compile.

Workaround:
\score { \new Devnull { s1 } \header { piece = "Stück" } }
Not sure whether this will always work, though.
And due to Devnull
programming error: system with empty extent
will persist, not(?) related to the reported assertion failure, though.


Cheers,
  Harm