Problem with repeats: stray bar line

[Tobias Braun]

Hi,

I have a weird problem with repeats that I just can't figure out. I've read the 
docs and tried different things for hours now, to no avail. Here's my minimal 
example:

%%%%%%%%%%%%%%%%%%%%%%%%%%

\version "2.18.2"

\relative c' {
        \partial 4
        \repeat volta 2 { c4 | c c c c | c c c }
        \repeat volta 2 { d4 | d d d d | }
        \alternative { { e4 e e } { f4 f f \bar "|." } }
}

%%%%%%%%%%%%%%%%%%%%%%%%%%

Can anyone tell me why I get that stray bar line after the first note in the 
second group of the \alternative expression?

Thanks,
Tobias