Phrasing slur bug?

[Stewart Holmes]

Hi,

Try the following example:

%%% code begins

#(define (pagebreakone grob)
            (let* (
                   ; have we been split?
                   (orig (ly:grob-original grob))
          
                   ; if yes, get the split pieces (our siblings)
                   (siblings (if (ly:grob? orig)
                               (ly:spanner-broken-into orig) '() )))
          
             (if (and (>= (length siblings) 2)
                       (eq? (car (last-pair siblings)) grob))
               (ly:grob-set-property! grob 'control-points '((0 . 0) (5 . 5) 
(10 . 15) (15 . 0))))))

\relative
{
        \override PhrasingSlur #'after-line-breaking = #pagebreakone    
        c \( d e f | \break
        c d e f \) | \break

        c  d \( e f | \break
        c d e f \) | \break

        c  d e \( f | \break
        c d e f \) | \break

        c  d e f \( | \break
        c d e f \) |
}

%%% code ends

Notice how the scheme code only 'works' in the first instance, and that the 
only thing changed in the four examples is where the phrasing slur starts. 
Unless there's some peculiarity I'm unaware of, this seems like a bug.

Thanks,
Stewart