stopStaff combined with StaffGroup extents barlines

[Toine Schreurs]

I am typesetting a score, where one of the staffs contains an ossia section.
I started from the example in section 1.6.1 of the NR. The second staff
will contain the ossia section. In the resulting score it is not obvious
to which staff this ossia belongs.
To connect the staff with the ossia section, I combined them into a StaffGroup.
Now it is clear to which staff the ossia belongs. But, all barlines are
(wrongly) extended also.
This behaviour started with version 2.11.35

Any hints?

Toine Schreurs

%======= start =========
\version "2.11.38"
musicOne =  \relative c' {
  \time 2/4
  d4 d |
  a' a |
  b b |
  f2
}

musicTwo =  \relative c' {
  e4 e |
  b' b |
  c c |
  g2
}

ossia =  \relative c' {
  \stopStaff
  s2*2 |
  \startStaff
  bes'8^"ossia" g bes g |
  \stopStaff
  s2 |
}

\score {
  <<
    \new Staff \musicOne
    \new StaffGroup 
      <<
        \new Staff \with
        {
          \remove "Time_signature_engraver"
          fontSize = #-2
          \override StaffSymbol #'staff-space = #(magstep -2)
          firstClef = ##f
        }
        \ossia
        \new Staff \musicTwo
      >>

  >>
}
%======== end ==========