Lilypond Crash on the following simple Code

[Beat Stoecklin]

The following Code produces a Crash on my Win XP

BTW: \markuplines should be storable in a Variable.

\version "2.12.3"

Varname = 
        \markuplines{  }

\book{
        \bookpart{
                \Varname
                \score {
                        c'4
                }
        }
}