[AUCTeX] Unfillable paragraph with AUCTeX 11.86

[Tassilo Horn]

Hi all,

I have a tex file containing this line/paragraph:

--8<---------------cut here---------------start------------->8---
VIATRA2\footnote{\url{http://www.eclipse.org/gmt/VIATRA2/}, last visited 
04.11.2010} (\emph{VIsual Automated model TRAnsformations}) is a 
general-purpose framework for engineering model transformations.  For 
representing both metamodel and models, the framework provides its own 
representation called \emph{VPM model space}.
--8<---------------cut here---------------end--------------->8---

Hitting M-q on it with a fill-column of 79 fills is to

--8<---------------cut here---------------start------------->8---
VIATRA2
\footnote{\url{http://www.eclipse.org/gmt/VIATRA2/}, last visited 04.11.2010} 
(\emph{VIsual Automated model TRAnsformations}) is a general-purpose framework 
for engineering model transformations.  For representing both metamodel and 
models, the framework provides its own representation called \emph{VPM model 
space}.
--8<---------------cut here---------------end--------------->8---

which is not what I would expect.  If I put an active region around the
paragraph and hit M-q again, it is filled to

--8<---------------cut here---------------start------------->8---
VIATRA2 \footnote{\url{http://www.eclipse.org/gmt/VIATRA2/}, last visited
04.11.2010} (\emph{VIsual Automated model TRAnsformations}) is a
general-purpose framework for engineering model transformations.  For
representing both metamodel and models, the framework provides its own
representation called \emph{VPM model space}.
--8<---------------cut here---------------end--------------->8---

which is what I expect.

What's the problem with that single paragraph?  All other paragraphs
fill just fine.  Maybe the nested parens and braces confuse
`LaTeX-fill-paragraph'?

Bye,
Tassilo