I'm not sure if this is intended, but when expanding a skeleton
(e.g. using sgml-tag), I sometimes change my mind and press C-g. I'm
then left with a half finished HTML tag, like for example

     <a id="

that is really never intended. The patch below ensures that all
skeletons are either inserted correctly, or cleaned up as part of an
atomic change group.

I didn't thoroughly investigate each instance of define-skeleton I could
find, but from skimming the places I found examples, it seems like this
change shouldn't break any expected behaviour.

-- 
	Philip K.