2 % mmrests of second voice should not disappear
4 % the problem is more complex: the mmrest-engraver lives at staff level,
5 % but it seems that we need one per voice.
9 \context Staff = Viole <
10 \context Voice=one \partcombine Voice
12 % ordering significant ??
13 \context Thread=two \relative c''{ R1 c2 c2 }
14 \context Thread=one { R1*2 }
21 \remove Multi_measure_rest_engraver;
26 \consists Multi_measure_rest_engraver;
27 \consists Bar_engraver;