bug#45839: 28.0.50; Isearch and transient mode wierd behaviour in info-mode!

[Juri Linkov]

> In info-mode do the following:
> + C-SPC :: set mark
> + C-s valid_query :: search for some string
> + RET
>
> By now you can see region is not highlighted and this will affect all
> other command such as M-w(kill-ring-save).

Please see in the function 'Info-search' that it intentionally
deactivates the active region during the search by calling:

  (deactivate-mark)

This is because when the search arrives in another Info node,
then region highlighting breaks - the region's beginning stays
in the previous node, while the region's end moves to the next node.
To avoid such situation, it deactivates the active region.

If you want to copy the region with M-w, then you can reactivate it with
'C-x C-x'.