MIDI: #'instrument mode: do not re-initialize channel with empty instrument.

diff --git a/lily/staff-performer.cc b/lily/staff-performer.cc
index 2fd85fe48286920492a440b77fc1e7b4cccf357e..502c289e0c9d2ccd943955e9bc7629d5a468ab27 100644 (file)
--- a/lily/staff-performer.cc
+++ b/lily/staff-performer.cc
@@ -261,7 +261,7 @@ Staff_performer::acknowledge_audio_element (Audio_element_info inf)
       string str = new_instrument_string ();
       if (channel_mapping != ly_symbol2scm ("instrument"))
        channel_ = get_channel (voice);
-      else if (str.empty ())
+      else if (channel_ < 0 && str.empty ())
        channel_ = get_channel (str);
       if (str.length ())
        {