Unification result for Prolog lists with variables recorded incorrectly

[kayceesrk]

Consider the query,

?- L = [1,2 | X]

SWI-Prolog interpreter correctly returns L = [1,2 |X] indicating that L is a list with prefix [1,2]. However, the similar program written using pyswip:

from pyswip import Prolog
prolog = Prolog()
for soln in prolog.query("L = [1,2 | X]"):
    print(soln["L"])

prints [1,2] saying that L is the list [1,2]. It should be [1,2 | X] or similar.

But it does not appear to be a unification issue since the following query unifies correctly, but is still displayed incorrectly:

from pyswip import Prolog
prolog = Prolog()
for soln in prolog.query("L = [1,2 | X], X = [3 | Y]"):
    print(soln["L"])

prints [1,2,3]. It should be [1,2,3 | Y] or similar.