How did that happen?

[Harald Hanche-Olsen]

I just had emacs getting into this strange state: Everything seemed
normal, except for one little thing: The cursor would jump to the
beginning of the line after I inserted any character. This happened
everywhere, including in the minibuffer.

Needless to say, this made emacs difficult to use to say the least.
The only thing I could think of checking was if something had gotten
into after-change-functions, but its value was as expected:
(mew-draft-dynamic-highlight t), global value nil. (What fun to type
stuff like C-h v -retfa C-e -ahc C-e nuf TAB in order to investigate!)

Unfortunately, I haven't the faintest idea how to trigger this
behaviour, or I would submit a bug report right away.

Does anyone here have any notion what could possibly trigger this
behaviour? Or suggestions for what I might try, should I encounter it
again? I had to terminate that instance – it is just too painful to
run two instances of emacs simultaneously, or I might have kept it
around so I could investigate it some more.

Version info:
GNU Emacs 24.4.50.1 (x86_64-apple-darwin13.4.0, NS appkit-1265.21
Version 10.9.5 (Build 13F34)) of 2014-09-27 on airy

Built from this commit:
commit 13559b3ff594d19244a691ddaf966e0965654537
Author: Stefan Monnier <address@hidden>
Date:   Sat Sep 27 12:26:54 2014 -0400

    * lisp/epg-config.el (epg-gpg-program): Use the plain program names rather
    than their absolute file name.

– Harald

PS. Sorry if posting to this list is inappropriate, but I suspect this
is too esoteric to fit on help-gnu-emacs. Correct me if I'm wrong.