Term expansion is unexpectedly not confined to its module

[triska]

For instance, with m.pl comprising:

:- module(m, []).

term_expansion(a, b) :- write(hello).

and p.pl comprising:

:- use_module(m).

a.

I get:

$ scryer-prolog p.pl
hello

The term expansion defined in m.pl is expected to be confined to that module, and should not affect the fact a. which is defined in p.pl.