MIDI tmpfiles containing spurious whitespace on Windows
LilyPond writes MIDI output to a temporary file that gets renamed afterwards.
On Windows, these files contain spurious whitespace, like
foo.mid. 3d1b
To reproduce this, take an arbitrary LilyPond file generating MIDI output, compile it, open the resulting file with a MIDI player and try compiling a second time while the MIDI file is still in use.