top level: infinite list represented incorrectly

[UWN]

?- call_nth(select(E, Xs, Xs),2).
   Xs = [_A,E|E], unexpected.
?- call_nth(select(E, Xs, Xs),2), Xs = [a,e|e].
   false. % proof that above answer substitution is incorrect
?- call_nth(select(E, Xs, Xs),2), Xs = [_A|_B], _B=[E|_B].
   Xs = [_A,E|_B], _B = [E|_B]. % the actual, expected one

[flexoron]

$ scryer-prolog -f
?- use_module(library(iso_ext)).
?- use_module(library(lists)).
?- [_|X] = X, call_nth(select(_,Xs,Xs),3), Xs=X, Xs=[x|Z].   % narrow list down to 3 [x,x,x|...]
   X = [x|X], Xs = [x,x,x|x], Z = [x,x|x].                   % Xs=[x,x,x as expected but with issue |x].
?- [_|X] = X, call_nth(select(_,Xs,Xs),3), Xs=X, Xs=[x,x|Z]. % 2 or more [x,x,...|Z]
   X = [x|X], Xs = [x,x,x|Z], Z = [x|Z].                     % issue vanished.

Though

?- [_|X] = X, call_nth(select(_,Xs,Xs),3), Xs=X, Xs=[x,x|Z], write_term(Xs,[max_depth(8)]),nl.
[x,x,x|x] % issue revealed
   X = [x|X], Xs = [x,x,x|Z], Z = [x|Z].
?-

[vihaanjim]

?- X=[0|L], L=[0|L].
   X = [0,0|L], L = [0|L]. % correct
?- use_module(library(lambda)).
?- X+\ (X=[0|L], L=[0|L]).
   X = [0,0|0]. % incorrect