When run on the attached file, lilypond-book sets the line length of the
music to be much less than the actual width of the page that latex is
using (which you can see by where it puts the footers.)

If you run:

   lilypond-book --pdf test.lytex
   pdflatex test.tex

you can see this.

If you comment out the \usepackage{geometry} line that has "landscape",
and use the line for portrait geometry, the line length of the music is
set correctly.

The landscape version works correctly in lilypond 2.12, but not in 2.14
or 2.15.