error and bad output with VoltaBrackets/ossia-staffs/RemoveEmptyStaves/repeats

[Thomas Morley]

Hi all,

with this code:

\version "2.18.2" %% up to "2.19.40"

\version "2.18.2"

\paper { indent = 20 short-indent = 20 }

\layout {
  \context {
    \Score
    \override VerticalAxisGroup #'remove-first = ##t
  }
  \context {
    \Staff
    \RemoveEmptyStaves
  }
}


mI = {
  c1
  \break
  \repeat volta 2 { d }
  \alternative { { e } { eis } }
  \repeat volta 2 { f }
}

mII = {
  c1 d e eis
  <<
    { f }
    \context Staff = "down-ossia" { fis }
  >>
}

<<
  \new Staff = "up-ossia"
    \with { instrumentName = "up-ossia " shortInstrumentName = "up-ossia " }
    { $(skip-of-length mI) }
  \new Staff
    \with { instrumentName = "up " shortInstrumentName = "up" }
    \mI
  \new Staff
    \with { instrumentName = "down" shortInstrumentName = "down" }
    \mII
  \new Staff = "down-ossia"
    \with { instrumentName = "down-ossia " shortInstrumentName = "down-ossia" }
    { $(skip-of-length mII) }
>>


I get
programming error: could not find this grob's vertical axis group in
the vertical alignment
continuing, cross fingers

and the gap between the VoltaBrackets is messed up.

This happens only if \RemoveEmptyStaves is enabled
and
the sequence is repeat+alternative directly followed by another repeat
and
_two_ ossia-staffs are present
and
stuff is sent to the _lower_ ossia-stuff at the time the second repeat starts.



Currently I've no clue what happens and would be very happy someone
could suggest a workaround.
It took me already a _long_ time to boil it down to the code below.
In "could not find this grob's vertical axis group" the term "this" is
not very specific and without any location it's a hard task to find it
in file with more than 16000 lines ...

Cheers,
  Harm