Ossia too long at key change

[Peter Van Kranenburg]

Dear List,

If right after an ossia there is a key change in the other parts, the 
staff of the ossia extends with the length of the key signature. See 
below for an example. I can't figure out how to make the ossia stop 
right at the bar line.

I tried to do \set Staff.explicitKeySignatureVisibility = #all-invisible
in the ossia staff, but that didn't work.

Thanks.
Peter


\version "2.18"

<<
  \new Staff = "ossia" \with {
    \remove "Time_signature_engraver"
    \hide Clef
    fontSize = #-3
    \override StaffSymbol.staff-space = #(magstep -3)
    \override StaffSymbol.thickness = #(magstep -3)
  }
  { \stopStaff s1*6 }

  \new Staff \relative c' {
    c4 b c2
    <<
      { e4 f e2 }
      \context Staff = "ossia" {
        \startStaff e4 g8 f e2 \stopStaff
      }
    >>
    \key a \major g4 a g2 \break
    c4 b c2
  }
>>