Strange barline appearance

[Michael Käppler]

Hi,
why does the barline look so strange in this example?
I can't remember having experienced this with older Lily, but 2.11.33 
seems to behave the same way.

Greetz,
Michael

\version "2.11.34"

\score {
<<
  \new StaffGroup <<
    \new Voice = "VoiceI" \relative c'' { g1 \bar "||" }
    \new Lyrics \lyricsto VoiceI \lyricmode { bla }
    \new Voice = "VoiceII" \relative c'' { g1 }
    \new Lyrics \lyricsto VoiceII \lyricmode { bla }
    \new Voice = "VoiceIII" \relative c'' { g1 }
    \new Lyrics \lyricsto VoiceIII \lyricmode { bla }
  >>
 >>
\layout {
  \context {
  \Lyrics
   \consists "Bar_engraver"
     \consists "Separating_line_group_engraver"
    \override BarLine #'transparent = ##t
  }
}
}