Problems with Lilypond chordChanges property

[Janne Kivijarvi]

%{

Hi!

I'm having a problem with the chordChanges property.

Down there's a simple melody with lyrics and chords. The chord 
is C major all the time and if I've understood things correctly, the
chordChanges property should prevent the symbol 'C'  from being printed
more than once per row. Well, at least on 1.3.129 it doesn't seem to 
do that for me.

Instead, the chord symbol is printed 4 times (the third bar doesn't get
one so something _is_ happening in there).

If I print the chord notes instead of the melody (by commenting out the
line '\context Staff \melody' and uncommenting the one below it), the
chord symbols turn out as expected i.e. just once.

Also, is there a standard way of stating that (for example) the first 
bar shouldn't have a chord (symbol) at all? An empty chord symbol
or a "no chord" chord?

Janne

%}

\version "1.3.129";

melody = \notes \relative c'{
        \property Staff.automaticMelismata = ##t
        c2 d | d1 | c2 d | c e | f g }

accomp = \chords { c1 c c c c}

verse = \lyrics {
        foo bar foo bar foo bar foo bar foo }           

\score { 
        \notes 
        <
                \context ChordNames \accomp
                \addlyrics
                \context Staff \melody
%               \context Staff \accomp
                \context Lyrics \verse
        >

        \paper {
                \translator {
                        \ChordNamesContext
                        chordChanges = ##t
                }
        }
}