[AUCTeX] Filling comments in LaTeX mode seems to be broken

[Alexander Shukaev]

Hello,

Open some TeX file or run a LaTeX/FP mode in some buffer.  Set `fill-column' to 80.  Copy/paste the following comment:

% Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Donec hendrerit tempor

% tellus. Donec pretium posuere tellus. Proin quam nisl, tincidunt et, mattis

% eget, convallis nec, purus. Cum sociis natoque penatibus et magnis dis

% parturient montes, nascetur ridiculus mus. Nulla posuere. Donec vitae

% dolor. Nullam tristique diam non turpis. Cras placerat accumsan nulla. Nullam

% rutrum. Nam vestibulum accumsan nisl.

so that the word "tempor" exceeds the `fill-column' limit by 2 letters.  Select the whole comment and `fill-region'.  My result looks terrible:

% Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Donec hendrerit

tempor % tellus. Donec pretium posuere tellus. Proin quam nisl, tincidunt et,

mattis % eget, convallis nec, purus. Cum sociis natoque penatibus et magnis dis

% parturient montes, nascetur ridiculus mus. Nulla posuere. Donec vitae %

dolor. Nullam tristique diam non turpis. Cras placerat accumsan nulla. Nullam %

rutrum. Nam vestibulum accumsan nisl.

Is this a bug or do I miss something?  Thanks in advance.

Kind regards,

Alexander