Assertion error in lilypond 1.6.6

[Larry Gilbert]

I know you're already working on 1.7.x, so I don't know if bugs like 
this are relevant anymore, but I thought I'd send it just in case.  I 
got the following error after a recent run of ly2dvi 1.6.6:

lilypond: ../flower/include/drul-array.hh:26: Real & 
Drul_array<double>::elem(Direction): Assertion `d==1 || d== -1' failed.
error:

LilyPond crashed (signal 6).Please submit a bug report to 
address@hidden

Traceback (most recent call last):
 File "/usr/bin/ly2dvi", line 1014, in ?
   run_lilypond (files, dep_prefix)
 File "/usr/bin/ly2dvi", line 516, in run_lilypond
   error ("\n\n" + _ ("LilyPond crashed (signal %d).") % signal \
 File "/usr/bin/ly2dvi", line 151, in error
   sys.exit (2)
SystemExit: 2