Bug: eigths-bars overlap in choirstaff

[Sietse Brouwer]

When I use the template for SATB vocal score from the manual,
and both the altos and the tenors sing a c' in eights, then 
the bars that connect the eights notes overlap. See below example.

I've searched the archives, and found no mention of that bug; 
if I used the wrong terms, and missed a prior mention, I'm sorry.

\version "2.8.1"
\paper{
  ragged-right = ##t
}
global = {
  \key c \major
  \time 4/4
}
notes = {
  c2. c8 c8  
}
sopMusic = \relative c'' {
  \notes
}
altoMusic = \relative c' {
  \notes
}
tenorMusic = \relative c' {
  \notes
}
bassMusic = \relative c {
  \notes
}
\score {
   \new ChoirStaff <<
      \new Staff = women <<
         \new Voice =
           "sopranos" { \voiceOne << \global \sopMusic >> }
         \new Voice =
           "altos" { \voiceTwo << \global \altoMusic >> }
      ]]
      \new Staff = men <<
         \clef bass
         \new Voice =
           "tenors" { \voiceOne <<\global \tenorMusic >> }
         \new Voice =
           "basses" { \voiceTwo <<\global \bassMusic >> }
      ]]
   ]]
}
* And I do wonder why the post.gmane.org programme tells me I'm 
top posting. I hope including this line fixes that.
* Hokay, so it doesn't. Maybe I'll move my signature & stuff 
to the bottom. Will that help?
* So that didn't help. I am quite close to giving up.
I'll try replacing the right-pointing brackets by ]]; maybe those are the 
problem. Remember to undo this when compiling the code.

Sincerely,

Sietse Brouwer, 
sbbrouwer 'monkeytail' gmail 'spot' com
Utrecht, the Netherlands