\midi plays straight through repeat marks

[Michael Hendry]

The following code demonstrates the fault. The resulting midi file consists of
twelve notes, ascending a major scale from C to G', instead of the expected
sixteen notes.


\version "2.12.3"
\score {
\repeat volta 2
{c4 d e f}
\alternative {
  {g a b c'}
  {d' e' f' g'}
}
\midi {}
}