bug#4136: 23.1; delete-pair

[martin rudalics]

> The exact reverse is impossible.  For instance, put the cursor
> on the letter `f' in:
>
>     foo "" bar
>
> and type `M-3 M-"' where M-" is bound to `insert-pair'.
> The result will be:
>
>     "foo "" bar"

Obviously `insert-pair' would have to escape the old quotes here ;-)

martin, who couldn't resist