copy_term/2 is incompatible with SICStus

[infradig]

With SICStus it is defined as equivalent to:

    copy_term(X, Y) :-
             assert('copy of'(X)),
             retract('copy of'(Y)).

and thus doesn't copy attributes, whereas Scryer copies the attributes a la SWI (one of the few occasions where it favours the latter).

SICStus copy_term/2 is thus similar to copy_term/3.

Note SWI has...

duplicate_term/2        % copy attrs
copy_term_nat/2         % doesn't copy attrs 
copy_term/2                % copy attrs