bug#27442: Un-obsolete x-clipboard-yank, or provide analogous functional

[Stefan Monnier]

> *ponder* Well, I guess it's a vague kind of DWIM thing going on...
> Since we don't have timestamps on our own kills, and
> `select-enable-clipboard' defaults to t, we want to let a clipboard
> selection "win" if we haven't yanked it before?  But...  it seems to me
> like this is already handled by other logic when putting things on the
> kill ring in the first place.

That pretty much matches my understanding, yes.

> That is, if you "emacs -Q", put something on the clipboard from a
> different programme, and when `M-w' something in Emacs, then `C-y' will
> insert the latter.

Yes, IIUC this is the easy case.  I think the harder case is when we
`M-w` first and then put something on the clipboard with another
application, then do `C-y`.

> I've tested various things here now, and I'm unable to come up with a
> scenario where the current DWIM logic is helpful, really.

Yet AFAICT the kill-ring logic was there already when the clipboard
logic was added, so I'm not sure the duplication is completely redundant.


        Stefan