Lyrics placed on rest but free notehead available

[Karl-Johan Karlsson]

The snippet below results in the "in" of "inter" (second voice, third bar, 
first syllable) being placed on the rest at the end of the second bar, with 
the rest of the lyrics of that voice moved one note left with it, leaving 
the last note without lyrics (see screenshot at 
http://www.lysator.liu.se/~creideiki/lilypond.png). Removing the first 
voice results in the second voice being printed correctly 
(http://www.lysator.liu.se/~creideiki/lilypond-2.png). Since this shows up 
in such a simple test case, I assume it is caused by me doing something 
wrong, and not by a bug in Lilypond. But what should I do to get it right?

Versions 1.5.68 and 1.5.70 complained about "Lyrics found without a 
matching notehead", but 1.6.0 does not give any error messages. All three 
produce the same output.

\score {
   \notes {
      \clef violin
      \time 8/8
      \key des \major
      < \context Voice = one {
         \voiceOne
         \addlyrics
         \notes {
            bes'4 bes' bes' bes'
            bes' aes' aes'2
            bes'4 bes' bes' bes'
            bes' des''2.
         }
         \context Lyrics \lyrics
         {
            Do __ mi __ nus ex __ au __ di nos
            do __ mi __ nus mis __ re __ re
         }
        }
        \context Voice = two {
         \voiceTwo
         \addlyrics
         \notes {
            ees'8 ees' ees' ees' ees' ees' r ees'
            des' des' des' des' des' des' des' r
            ees' ees' ees' ees' ees' ees' r ees'
            des' des' des' des' des' des' des' r
         }
         \context Lyrics \lyrics
         {
            Do __ na no __ bis pa __ cem e
            do __ na eis re __ qu __ i __ em
            in __ ter o __ vas lo __ cum vo
            __ ca me cum be __ ne __ dic __ tis
         }
        }
      >
   }
   \paper {}
}


Karl-Johan "Creideiki" Karlsson
--
* They stand in my road,
   The mad, ancient, nasty things
      Tell them "move, or else!" *