Completion_heads_engraver broken?

[Michael Käppler]

Hello,
I'm transcribing a few pieces of late Renaissance polyphony and wanted 
to use the Completion_heads_engraver to automatically split long notes, 
as described in the manual. But all I get is a kind of an endless loop 
or something.
Lily halts at "Interpretation der Musik... [8] [16]" and nothing happens.
As far as I remember, Lily failed in any of the later 2.11. releases 
with segfault in the same case. Is this a known issue?
Otherwise I could try to cook a minimal example.

Regards,
Michael