Strange spacing

[Thomas Scharkowski]

The example below produces a quite strange spacing in measure 2, the 
second note should be placed nearer to the first note.
When I remove bar on the spacing is o.k.

Thomas


\version "2.15.26"
upper = \relative c'' {
   \voiceOne
   \repeat unfold 8 {c32 c c c} |
   c4 c2 c4
}

lower = \relative c'' {
   \voiceTwo
   s1
   a2  a
}

\score
{
   <<
     \upper
     \\
     \lower
   >>
}