Can't align lyrics below ossia staff

[Dénes Harmath]

> I'm not top posting.

alignBelowContext seems to be ignored in this case:

\score { <<
  \new Voice = melody {
    \relative c' {
      c4
      <<
        { c8 e }
        \new Staff = ossiaStaff {
                \new Voice = splitpart { c4 }
        }
      >>
      c4 c | c
    }
  }
  \new Lyrics \lyricsto melody { we shall not o- ver- come }
  \new Lyrics \with {
        alignBelowContext = #"ossiaStaff"
  } \lyricsto splitpart { will }
>> }

If I insert the ossia lyrics context in the inner parallel music expression, the
output is erroneous as described in
http://lists.gnu.org/archive/html/lilypond-user/2011-03/msg00041.html:

\score{ <<
  \new Voice = melody {
    \relative c' {
      c4
      <<
        { c8 e }
        \new Staff = ossiaStaff {
                \new Voice = splitpart { c4 }
        }
        \new Lyrics \with {
                alignBelowContext = #"ossiaStaff"
        } \lyricsto splitpart { will }
      >>
      c4 c | c
    }
  }
  \new Lyrics \lyricsto melody { we shall not o- ver- come }
>> }

Can be reproduced with either 2.12.3 or with 2.13.52.