#4839 Skyliner misses beams after staff change

[Phil Holmes]

Malte Meyn reported:

the following code produces an incorrect skyline for the "rh" staff. It
includes the noteheads but not the stems and beam. This happens only
with certain rhythms (for example, 8. 16 in the "lh" staff produces a
correct skyline in the "rh" staff).

\version "2.19.40" % also 2.18.2, 2.16.2, 2.14.2

#(ly:set-option 'debug-skylines #t)

<<
   \new Staff = "rh" s2.
   \new Staff = "lh" {
     d'8 f''
     \change Staff = "rh"
     d'8. f''16
     \change Staff = "lh"
     d'4
   }
 >>