Shift-Insert overwrites ZLE CUTBUFFER

[lolilolicon <lolilolicon@xxxxxxxxx>]

I use Shift-Insert to paste the X PRIMARY selection in terminal.
But when I use Shift-Insert, the ZLE CUTBUFFER is also overwritten.
Is there a way to disable this?

Example, with cursor at the end of line,

% foo
^W kills "foo"
^Y yanks "foo", as expected
% foo
Shift-Insert pastes "bar", content of PRIMARY selection
% foobar
^Y yanks "bar", instead of "foo", unexpected!
% foobarbar