cross-staff ties do not work

[Rune Zedeler]

I thought this was a well-known limitation, but I cannot find it 
mentioned in the NR nor the tracker.

Ties do not work over staff changes:

\version "2.10.33"
<<
  \new Staff = staffa { s1 }
  \new Staff = staffb { \clef F c'2~ \change Staff = staffa c'2 }
>>

-Rune