Unable to reach minimum value of signed types

[shaobo-he]

Hello,

It appears this test will always pass even setting QUICKCHECK_TESTS and QUICKCHECK_MAX_TESTS to a large value (e.g., 10000000) and QUICKCHECK_GENERATOR_SIZE to 300,

fn prop_gt(x: i8) -> bool {
    x != i8::min_value()
}

fn main() {
    quickcheck(prop_gt as fn(i8) -> bool);
    println!("Hello, world!");
}

It appears these lines of code attribute to this issue,
https://docs.rs/quickcheck/0.8.2/src/quickcheck/arbitrary.rs.html#756-771
If upper = min(g.size(), $ty::max_value() as usize), then if upper > $ty::max_value() always evaluates to the else branch.