Parallel CueVoice with "too early" a clef change

[Menu Jacques]

Hello folks,

In the following, from Poulenc, I added a CueVoice to help the bassonnist (i.e. myself). The example is a bit long, sorry for that.

The critial point is on the second beat of the bar at the « 1 » rehearsal mark: the clef change to « bass » for the bassoon takes effect also for the oboe (Hbs), making the last a8 look abnormally high.

Is there a way to force it to be displayed in treble clef even though the (parallel) bassoon voice is in bass clef?

Thanks for the help!

JM

\version "2.19.30"

Basson =  \relative b' {
  \set Score.markFormatter = #format-mark-circle-numbers
  \compressFullBarRests

  \accidentalStyle Score.teaching

  \numericTimeSignature\time 2/4
  \tempo "Lent" 4 = 76

  \clef "bass"
  R2 |
  <<
    {
      \tweak staff-position #-6 R2*8 |
      \mark\default
      r4
      \cueClefUnset
      \clef "bass"
      gis,8 \f ( [ a8 ] | % 90
    }
    \new CueVoice {
      \relative {
        \set instrumentCueName = "Hbs"
        \cueClef "treble"
        %\stemDown
        %\slurUp
        \voiceOne
        \tweak staff-position #-1 r4
        gis'8 \mf \< ( a |
        b [ cis d e ] |
        fis2 -> ) \! ~ |
        fis4 e8 ( d |
        d4 cis ) |
        r8 cis ( [ bis cis ]  |
        e [ d b fis ] |
        fis4 gis |
        gis4
        a8 ) %%%%%% <==== here is the problem
        s |
      }
    }
  >>

  b8 [ cis8 d8 e8 ]
  \bar "||"

  \time 3/4
  fis2 e8 [ d8 ]
  \bar "||"

  \time 2/4
  d4 -\markup{\italic "céder à peine"} cis4 )
  \bar "||"
}

{ \Basson }