$ LilyPond.app/Contents/MacOS/python LilyPond.app/Contents/Resources/bin/convert-ly
Could not find platform independent libraries <prefix>
Could not find platform dependent libraries <exec_prefix>
Consider setting $PYTHONHOME to <prefix>[:<exec_prefix>]
'import site' failed; use -v for traceback
Traceback (most recent call last):
  File "LilyPond.app/Contents/Resources/bin/convert-ly", line 13, in <module>
    import os
ImportError: No module named os