Repeat volta/alternative with voices

[Zbyszek Loska]

Hi,
I am not an experienced user of lilypond, but this seems to me
as bug in parser, or, I do not understand something...
======================================
\version "2.15.43"

Upper = \relative c' {
  e2 g |
  \repeat "volta" 2 {
  c2 e |
  }
  \alternative {
    { <g, b> r } |
    { <g b> g } |
  }
}

Lower = \relative c {
  c'2 g |
  \repeat "volta" 2 {
  c2 e |
  }
  \alternative {
    { g, f } |
    { g g } |
  }
    \bar "|."
}

\score {
  \new Staff { << \Upper \\ \Lower >> }
  \layout { }
}
=======================================

... produces 2 warnings:

warning: More alternatives than repeats.  Junking excess alternatives

and output: "test_repeat_2_voices.png".
If I change all "\repeat volta 2" into "\repeat volta 3",

lilypond produces these same 2 warnings, but output is as expected:
"test_repeat_3_voices.png".

This happens in Lilypond ver. 2.12 and 2.14 as well.

Thanks,
Zbyszek Loska

test_repeat_2_voices.png
Description: PNG image

test_repeat_3_voices.png
Description: PNG image