When the final character on a line is a period, auto filling both with
do-auto-fill and with fill-paragraph incorrectly moves the entire word
preceding the period to the next line. This is not the case when it is
a letter in the fill-column.
To reproduce, `emacs -Q` Then load up this text in a buffer, and turn
auto-fill-mode on, and assuming that fill-column is set to 70.
Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eius.
Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusm
Both lines are the same except for the final character. If we type a
space at the end of both lines, the one word with a trailing period is
(incorrectly) moved to the next line, while the other does nothing.
This behaviour doesn't seem to be tied to the value of fill-column (I
tried it with a few 5 and 70).
I've attached a dribble file, starting from 'emacs -Q' that illustrates the
filling issues I'm talking about.