#5001 Beam disappears with TupletNumber.avoid-slur = #'outside

[Simon Albrecht]

Reported by Risto Vääräniemi.
See also discussion on the user list.

Starting somewhere between 2.19.25 and .29, the following code has the second beam squashed somewhat to the left edge of the type area (output attached):

\relative c'' {
  \tuplet 3/2 {a8( g a)}
  \override TupletNumber.avoid-slur = #'outside
  \tuplet 3/2 {a8( g a)}
}

Harm pointed out three potentially related issues
and gave some further test code:

suicideTN =
\override TupletNumber #'before-line-breaking =
  #(lambda (grob) (ly:grob-suicide! grob))

omitTN = \override TupletNumber #'stencil = #'()

hideTN = \override TupletNumber #'transparent = ##t

avoidSlurOutside = \override TupletNumber #'avoid-slur = #'outside

printTuplets =
#(define-music-function (parser location nmbr mus mus2)
(integer? ly:music? ly:music?)
#{
\relative c'' {
  $mus2
  $mus
  \repeat unfold $nmbr \times 2/3 { g8^( a) g }
}
#})

nr = 4

\markup \rounded-box \fill-line { "default" }

\markup "default"
\printTuplets #nr {}{}

\markup "suicide TupletNumber-grob"
\printTuplets #nr \suicideTN {}

\markup "omit TupletNumber.stencil"
\printTuplets #nr \omitTN {}

\markup "TupletNumber.transparent = ##t"
\printTuplets #nr \hideTN {}

\markup \rounded-box \fill-line { "avoid-slur : outside" }

\markup "default"
\printTuplets #nr {} \avoidSlurOutside

\markup "suicide TupletNumber-grob"
\printTuplets #nr \suicideTN \avoidSlurOutside

\markup "omit TupletNumber.stencil"
\printTuplets #nr \omitTN \avoidSlurOutside

\markup "TupletNumber.transparent = ##t"
\printTuplets #nr \hideTN \avoidSlurOutside