bug#7787: 23.2; wrong meaning for mouse-2 while in search mode

[Juri Linkov]

>   0. emacs -Q
>   1. M-: (setq mouse-yank-at-point t) RET
>   2. double click any word to mark it
>   3. C-s
>   4. mouse-2 [with cursor still over the original window, not in
>      minibuffer]
>
>> I see that the existing implementation of isearch-mouse-2
>> allows yanking the selection when clicked in the echo area,
>> but when clicked in the buffer it goes into infinite recursion,
>> because isearch-mouse-2 calls itself again.
>
> This is what I see as well, on current master.

The problem is that 'key-binding' in 'isearch-mouse-2'

  (let ((overriding-terminal-local-map nil))
    (key-binding (this-command-keys-vector) t))

still returns the keybinding from 'overriding-terminal-local-map'
that contains isearch keybindings.  Something is wrong here.