midiInstrument changes play one note too late.

[Michael Ellis]

Is this a known problem?  I don't see any prior reports online and
I've been seeing it since at least 2.12 but assumed it was because I
was doing some fairly complicated things.  I took time to reduce it to
a minimal example today. It's still present in 2.15.33 as shown by the
example below.  FWIW, I'm running OS X 10.6.7 and playing the midi
with QuickTime.  I'm attaching the midi file.

Is there a workaround?

Thanks,
Mike

%% Minimal Example
%% BUG? Midi instrument changes are delayed by one note.
mymusic = {

  \set midiInstrument = "acoustic grand"
  c'1^"pno." |  % midi ok

  \set midiInstrument = "cello"
  d'1^"cel." |  % wrong : midi plays piano.

  \set midiInstrument = "acoustic grand"
  e'1^"pno." |  % wrong : midi plays cello
  c'1^"pno." |  % midi ok

}

\score {

        \new Voice = "Test" { \mymusic  }
        \layout {}

        \midi {
            % This lets us specify instrument in melody
            \context {
                \Staff
                \remove "Staff_performer"
            }
            \context {
                \Voice
                \consists "Staff_performer"
            }
        }
    }

\version "2.15.33"

Cheers,
Mike

midi_late_instrument_change.midi
Description: MIDI audio