Fix expectation in hroller test

Regular expressions are not shell globs. So "any symbol" is expressed
by a dot, not a question mark. In this case, the confusion lead to a
too liberal expectation, hence the test passed. Fix it nevertheless.

Signed-off-by: Klaus Aehlig <aehlig@google.com>
Reviewed-by: Guido Trotter <ultrotter@google.com>