Slur as TupletBracket

[Jethro Van Thuyne]

I'm trying to replace the tuplet bracket with a slur by doing:

  \layout {
    \context {
      \Score 
      \override TupletBracket #'stencil = #ly:slur::print
    }
  }

Unfortunately, I get a fucked up slur, starting and ending vertically on 
the first note of the triplet (version 2.12.3):

  http://hemiola.eu/tuplet_slur.png

Is it broken or am I doing it wrong?

Best regards,

Jethro.