Bug in articulate.ly + TrillSpan + full-measure rests

[Davide Liessi]

Dear all,
I found a strange behaviour in the interaction of articulate.ly with 
TrillSpan and full-measure rests.
This snippet:

\version "2.19.15"
\include "articulate.ly"
\articulate {
  b1 \startTrillSpan |
  R1 \stopTrillSpan |
  b2 r |
}

gives a warning: barcheck failed at: 1/2
  b2 r
       |
and also b2 is expanded as a trill.
This happens both with the version of articulate.ly included in LilyPond 
2.19.15 and with the version in latest Git (i.e. with all the latest 
patches).

The warning disappears and the trill spanner stops in the right place in 
any of the following cases:
- change R1 to r1 in measure 2
- change r to b in measure 3
- remove \articulate (of course!)

How can I solve this problem?
Best wishes.
Davide