Ottava bracket outside-staff-priority

[Andrew Bernard]

I want to put an ottava bracket inside a tuplet bracket. Using the 
outside-staff-priority parameter, this will only work if the tuplet bracket 
priority is greater than 400, which is the default for the ottava bracket. I 
thought that it was a matter of numerical ordering to do this, not absolute 
values. Changing the value of outside-staff-priority for the ottava bracket 
value seems to have no effect. What am I missing?

Andrew

— snip

\version "2.19.28"

bass = {
  \clef bass
  \time 1/4
  \stemUp
  \tupletDown
  \once \override OttavaBracket.outside-staff-priority = #2
  \once \override TupletBracket.outside-staff-priority = #3

  %\once \override TupletBracket.outside-staff-priority = #401

  \override TupletBracket.bracket-visibility = ##t
  \tuplet 5/4 {
    <cis e b>8.[
    \once \override OttavaBracket.outside-staff-priority = #1
    \ottava #-1
    \set Staff.ottavation = #"8"
    <a,,, bes,,, ees,,>8]
    \ottava #0
  }
}

\score {
  \new Staff { \bass }
  \layout { }
}

— snip