comint: 'C-c RET' changed unfavorabily

[Nick Roberts]

 > I've just found that in emacs 22, the  key  'C-c RET' is bound
 > to something quite different than it used to be for many years
 > in previous emacsen.  For me and my fingers which are trained to use
 > C-c RET subconsciously almost, the new behavior is quite a pain:
 > 
 > Emacs 21.4 {from inside *shell* opened by M-x shell} :
 > 
 >    C-c RET runs the command comint-copy-old-input
 ...
 > 
 > Emacs 22 (version details below; from inside *shell* opened by M-x shell} :
 > 
 >    C-c RET (translated from C-c <return>) runs the command 
 > comint-insert-input

The two functions overlap (they both retrieve earlier input).  Can you give a
simple example of how you use comint-copy-old-input in a way that doesn't work
with comint-insert-input?

Nick