Lilypond 1.7.13 : 'programming error: Multi_measure_rest::get_rods (): I am not spanned!'

[Alexandre Beneteau]

Hello,

After posting to users mailing-list, and received advice to post on 
address@hidden, I send you this music source snippet which give the 
following warning :

Calculating line breaks... programming error: 
Multi_measure_rest::get_rods (): I am not spanned! (Continuing; cross 
thumbs)

here is the code :

\include "italiano.ly"

\score {
  \notes {
  \time 3/4
  R2.*3
  \time 2/4
  \grace {s8} % Have to do this to avoid bug signaled in the manual 
about grace notes (an other voice has a grace note at the beginning of 
this measure)
  R2*3
  }
}