Unexpected scope of cut in a If-Then construct

Given the following test file:
```prolog
t :- a, (! -> true).

a.
a.
```

This query seems to cut too many choice points:
```prolog
?- t.
   true.
```

I've expected it to succeed 2 times, but it succeeds only once.

On the other hand the query that must be equivalent behaves as expected:
```prolog
?- a, (! -> true).
   true
;  true.
```