bug#3619: Replace Rectangle can't do empty after first replace anymore

[Stefan Monnier]

> sinve emacs V22 theres 
> String rectangle (default foobar): 
> Now one can override foobar by a new text, but theres no way to get it
> do the same as C-x r k does, which is actualy convenient because one
> doesn't have to remember two commands.

Actually, C-x r d is the equivalent (since C-x r k additionally stores
the killed text on the kill ring).  And yes, this was a known tradeoff
when introducing the new behavior in Emacs-22.


        Stefan