Problem with snippet 654 after 2.15.28

[Phil Holmes]

Up until 2.15.27 http://lsr.dsi.unimi.it/LSR/Item?id=654 runs OK. 
Afterwards it seems to loop infinitely.  I've tried convert-ly and it left 
the snippet unchanged.  Could someone who understands what it's doing check 
whether a lily syntax change is needed, or is it revealing a bug?

--
Phil Holmes