Emacs trunk BZR sometimes hangs when using auto fill mode with PG Coq

[coquser]

The devlopment version (BZR trunk) of Emacs can hang when PG Coq is used together with Emacs' auto fill minor mode. You can, for instance, reproduce the error in the following way:

1. Start Emacs without any initialization; emacs -q -nsl
2. Load PG initialization: M-x load-file <path-to-PG>/generic/proof-site.el
3. Open a *.v file.
4. Activate auto fill mode: M-x auto-fill-mode
5. Place the cursor _afer_ a comment with more than `fill-column' many characters.
6. Press <enter> -> Emacs hangs, and must be killed.

Remark 1: You do not get an error if auto filling happens _inside_ a comment.

Remark 2: Emacs 24.2.1 does not have this problem at all.

[coquser]

The problem boils down to the function smie-auto-fill in lisp/emacs-lisp/smie.el. Ticket #13942 in the Emacs bugtracking system takes care of this. So this ticket can be closed.