transparent notehead bug

[David Bobroff]

I think this is a bug.  The following code when run in plain lilypond
produces an error message:


 warning: note head `noteheads-2transparent' not found:
        c d e f g \inv 
                       a \unv b c

But does produce output.  That output is also flawed, in that the stem
of the invisible note is visible as two vertical dashes.

Version 2.1.28 (CVS ChangeLog 1.1795)

inv = {
     \override Staff.NoteHead  #'style = #'transparent
     \override Stem  #'transparent = ##t
     \override Accidental #'style = #'transparent
}

unv = {
    \override Staff.NoteHead  #'style = #'default
    \override Stem  #'transparent = ##f
    \override Accidental #'style = #'default
}

\score {
    \notes {
        c d e f g \inv a \unv b c
    }
}