bug#9185: 24.0.50; "C-s M-p" does not bring the tip of the search ring

[Juri Linkov]

> If that is the resulting behavior, it is indeed a problem, but a small
> one IMO.  Since `C-s C-s' retrieves the first entry from the search
> ring, `M-p' should retrieve the _previous_ one, i.e., the second.

This complicates the behavior of `M-p'.
Do you propose the following logic?

1. When the user starts Isearch with `C-s', then
   `M-p' should retrieve the _first_ entry from the search ring.

2. But when the user starts Isearch with `C-s C-s', then
   `M-p' should retrieve the _second_ entry from the search ring.

But what to do when the user starts Isearch with `C-s C-s', but
changes his mind and deletes it from the current search string,
i.e. types `C-s C-s DEL'.  What should `M-p' bring in this case?
The first or the second entry?