Weird behavior for after-line-breaking

[Paolo Prete]

Hello,

please consider the following snippet. The procedure called at
after-line-breaking doesn't do *anything*,  but a weird space is added
between staves.
If you remove the \override line OR the \tuplet, this doesn't happen
Why?? Is there a fix for this?
The error happens for both 2.18 and 2.19

Thanks!

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#(define (afterLineBreakingfoo grob)
(let* ((origsten (ly:grob-property grob 'stencil)))
          (display "foobar")))

upper = {

\override TupletBracket.after-line-breaking = #(lambda (grob)
(afterLineBreakingfoo grob))
\tuplet 3/2 {c'4 \change Staff = "lower" c'' g''}

} %end upper



lower = { s4 s s}

\score {
  \new PianoStaff <<
    \new Staff = "upper" \upper
    \new Staff = "lower" \lower
  >>
  \layout { }
  \midi { }
}

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