bug report

[Pierre]

%bug report. This is a lilypond file
% at a same time : remove empty staff is on an end,
% and the alto voice is changing staff.
% just before,  la fa stems end at the middle
% of the staff and no beams are printed
%but good printing with  instead la [fa]
\version "2.12.3"
\include "italiano.ly"

soprano = \relative
 { \time 2/4
sol''2
sol
sol }

alto = \relative
 {
s2
re8  re la fa %but good printing with re8  re la [fa]
\change Staff = basse
mi2 }

tenor =  {  \clef bass
do2
s2
s2 }

\paper { system-count = #3  ragged-bottom = ##t }

\score { \new PianoStaff << \new Staff = dessus
 { << \soprano \\ \alto >> }
\new Staff = basse  \tenor >>

\layout{ \context { \RemoveEmptyStaffContext }
\context { \Score
\override VerticalAxisGroup #'remove-first = ##t } }
}