Extenders are not printed for lyrics associated with multi-staff contexts

[Alexander Kobel]

Dear all,

since the advent of 2.19.50, it is possible to attach lyrics to 
different contexts than just a voice:  "The \addlyrics function now 
works with arbitrary contexts incuding Staff."
Indeed, for Staves, it works like a charm AFAICS.  However, when 
attached to a ChoirStaff, GrandStaff or StaffGroup, no extenders are 
generated.  (Nb: the *alignment* with notes / music columns works 
perfectly fine, just the extender generation fails.)

Attached is a test case.  The lyrics lines for the three multi-staff 
contexts should look like the single-staff line, as far as I can tell.


Best,
Alexander

lyr-ctx.ly
Description: Text Data

lyr-ctx.png
Description: PNG image