>>> While we're improving isearch, there is another minor change that I 
>>> think would improve its behavior, namely to go to the next/previous 
>>> match when changing the search direction, instead of hitting the same 
>>> match before moving to the next/previous one with the next C-s/C-r. 
>>> This change is so small that I'm not sure it's worth creating a 
>>> defcustom for it, but you might have a different opinion.
>> 
>> Please do NOT do this.  There are reasons we want to stay at the same 
>> search hit.
>
> Okay, so I have the answer to my own question: this should become yet 
> another user option.
>

And here is the corresponding patch.