Linebreaking bug

[Rune Zedeler]

I managed to produce an a bit smaller example of wrong line-breaking.
The strange thing is that reducing the example further removes the bug.
Even commenting out the marked line removes the bug even though the line
is part of simultainous music in the same voice and with the same
rhythm.


\version "1.5.20"
piar = \notes \relative g' \context Voice {
  \clef "G_8" \key f \major
  \repeat unfold 3
  < {g8 a r16 a8 g16 r a8. g8 a | g8 a r16 a8 g16 }
    % comment out next line to produce correct line-breaking
    {f8 f r16 f8 f16 r f8. f8 f | e8 e r16 e8 e16 }
    {d8 d r16 d8 d16 r d8. d8 d | d8 d r16 d8 d16 }
    {b8 b r16 b8 b16 r b8. b8 b | b8 b r16 b8 b16 }
  >
  \alternative {
    {r16 c, d8  f d }
    {r8 c, d16 f8 <g16 f d b > ~ }
    {r8 c, d f }
  }
  < {e8  f r16 f8 e16 r f8. e8 f | g8. a g8 r16 a8. g8 a }
    {c,8 c r16 c8 c16 r c8. c8 c | e8. f e8 r16 f8. e8 f }
    {g,8 a r16 a8 g16 r a8. g8 a | c8. c c8 r16 c8. c8 c }
  >
}

pial = \notes \relative g \context Voice {
  \clef F \key f \major
  g,4 d' g, d' c g'8. c,16 r16 c d8  f d
  g,4 d' g, d' c g'8. c,16 r8 c d16 f8 g,16 ~
  g4  d' g, d' c g'8. c,16 r8 c d f 
  f,4 c' f,8. c'16~c cis8 d16~d8. d d8 r16 d8. a8 as
}

bas = \notes \relative g, \context Voice {
  \clef "F_8" \key f \major
  g,4 d' g8. f16 r g f d | c4 g'8. c16 r c, d8  f d |
  g,4 d' g8. f16 r g f d | c4 g'8. c16 r8 c, d16 f8 g,16 ~ |
  g4  d' g8. f16 r g f d | c4 g'8. c16 r8 c, d f | 
  f,4 c' f8. c16~c cis8 d16~d8. a' d8 r16 d,8. a8 as
}

\score {
  \notes <
    \context GrandStaff <
      \context Staff = up {
        \piar
      }
      \context Staff = down {
        \pial
      }
    >
    \context Staff = bas {
        \bas
    }
  >
  \paper {}
}