#5118 parenthesizing BreathingSign fails at line-end

[Thomas Morley]

As reported here:
http://lists.gnu.org/archive/html/bug-lilypond/2017-04/msg00010.html

If parenthesizing a BreathingSign right before a line-break, Lilypond engraves the parentheses on the next line to the left of the clef sign, rather than the line that it should be.

\version "2.19.59"

{ c'1 \parenthesize \breathe \break d' }

Log says:

programming error: Improbable offset for stencil: inf staff space
Setting to zero.
continuing, cross fingers

[Thomas Morley]

A workaround is not to use \parenthesize, but to parenthesize BreathingSign.stencil. Then BreathingSign.break-visibility works as expected.

xy =
  \once \override BreathingSign.stencil =
  #(lambda (grob)
    (parenthesize-stencil (ly:text-interface::print grob) 0.05 0.2 0.6 0.2))    

\relative c'' {
  b4 c d f \xy \breathe \break
  e d c \parenthesize \breathe a
}