bug#25906: 25.1; strange behavior of overlapped mouse-face

[Glenn Morris]

Eli Zaretskii wrote:

>> I expect expect the appearance of the display when the cursor is at some
>> point (BBB) to not depend on how it got there.
>
> I agree.  This should already happen after my recent changes.

Yes, that happens now, but not in the way I was naively expecting.
Now it seems that overlay ol-2 always wins. Maybe this is correct, I
don't know. I think from the original report, the OP might expect both
underline and overline when the cursor is on BBB, but there is now
always only overline.