Singleton variable in branch: right warning message?

This code gives the warning "Singleton variable in branch: A", but shouldn't it be a regular singleton warning?


p(X) :-
    (X > 0 ->
        A=1
        ;
        A=0
    ).
I spent time trying to figure out 
which branch was to blame (in more complex code), when in fact the branches are fine, it's just
 that the variable isn't used afterwards.


p(X) :-
    (X > 0 ->
        A=1
        ;
        A=0
    ),
    write(A).   % use variable A and the warning goes away.

Cheers,
Parker
 		 	   		  
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