Bug? 'inter-loose-line-spacing #'stretchability leads to collision

[Dmytro O. Redchuk]

> sorry being a Bug Squad member i can not decide is this a bug .)

Hi!

Excuse me, snippet is rather long --- whie i strip it to three notes and three
syllables, everyting is ok, i dont know for which reason. So, i've taken a
piece of real score and stripped/simplyfied it.

So, there are three lines of lyrics between staves, with 'staff-affinity set
to UP, CENTER and DOWN, everything is nice.

But if i specify 'inter-loose-line-spacing #'stretchability (see below),
spacing is ugly, see the image.

If this is a bug --- please! let me know :-)

Thank you!

%------------------8< ----------------------------
\version "2.13.25"

alto = \relative d' {
  \autoBeamOff
  %
  g4 g g g |
  g1 ~ |
  g4 c,8 c c4 c |
}

tenor = \relative b {
  \clef "bass"
  \autoBeamOff
  %
  e4 d c d |
  e4 g,8 g g4 g |
  g1 |
}

altolyrics = \lyricmode {
  \repeat "unfold" 5 { \skip 1 }
  по -- пе -- че -- "ні -" % -- є.
}

commonlyrics = \lyricmode {
  по -- пе -- че -- ні -- є,
}

tenlyrics = \lyricmode {
  \repeat "unfold" 5 { \skip 1 }
  по -- пе -- че -- ні -- є,
}

%
\score {
  \context ChoirStaff <<
    \new Staff = "upperstaff" <<
      \new Voice = "alto" {
        \voiceTwo
          \alto
      }
      \context Lyrics = "altolyrics" \with {
        \override VerticalAxisGroup #'staff-affinity = #UP
      } \lyricsto "alto" \altolyrics
      %
      \context Lyrics = "commonlyrics" \with {
        \override VerticalAxisGroup #'staff-affinity = #CENTER
      } \lyricsto "alto" \commonlyrics
    >>
    %
    \new Staff = "tenstaff" <<
      \new Voice = "tenor" {
        \voiceOne
        \tenor
      }
      \context Lyrics = "tenlyrics" \with {
        alignAboveContext = "tenstaff"
        \override VerticalAxisGroup #'staff-affinity = #DOWN
      } \lyricsto "tenor" \tenlyrics
    >>
  >>

  %
  \layout {
    \context {
      \Lyrics
        \override VerticalAxisGroup #'inter-loose-line-spacing #'stretchability 
= #3
    }
  }
}
%------------------8< ----------------------------

-- 
  Dmytro O. Redchuk
  Bug Squad

sample--no-stretch.png
Description: PNG image

sample--stretch.png
Description: PNG image