> I think it’s reasonable to insert an opening quote whenever there
> isn’t room for one behind the point. I’ve attached a patch that
> implements this behaviour.

If I had taken into account narrowed buffers it wouldn’t have seemed
so reasonable.

With this new patch, ‘TeX-insert-quote’ only tries to ‘forward-char’
in reverse when there’s enough room to do so. Unlike with the previous
patch, it can insert a closing quote even if there’s no room for an
opening one before point.