test-exercise script cuts out all lines which contain #[ignore]

[coriolinus]

Every line containing #[ignore] gets cut out entirely. This isn't desired behavior,
because it prohibits inline use of the attribute. In particular, the following (from #394):

tests! {
    test_classification {
        #[ignore] test_1(1, Classification::Deficient);
        #[ignore] test_2(2, Classification::Deficient);
        #[ignore] test_4(4, Classification::Deficient);
        #[ignore] test_6(6, Classification::Perfect);
        #[ignore] test_12(12, Classification::Abundant);
        #[ignore] test_28(28, Classification::Perfect);
        #[ignore] test_30(30, Classification::Abundant);
        #[ignore] test_32(32, Classification::Deficient);
        #[ignore] test_33550335(33550335, Classification::Abundant);
        #[ignore] test_33550336(33550336, Classification::Perfect);
        #[ignore] test_33550337(33550337, Classification::Deficient);
    }
}

gets trimmed down to:

tests! {
    test_classification {
    }
}

instead of the desired:

tests! {
    test_classification {
        test_1(1, Classification::Deficient);
        test_2(2, Classification::Deficient);
        test_4(4, Classification::Deficient);
        test_6(6, Classification::Perfect);
        test_12(12, Classification::Abundant);
        test_28(28, Classification::Perfect);
        test_30(30, Classification::Abundant);
        test_32(32, Classification::Deficient);
        test_33550335(33550335, Classification::Abundant);
        test_33550336(33550336, Classification::Perfect);
        test_33550337(33550337, Classification::Deficient);
    }
}

We have to fix this using the uglier pattern:

tests! {
    test_classification {
        #[ignore]
        test_1(1, Classification::Deficient);
        #[ignore]
        test_2(2, Classification::Deficient);
        #[ignore]
        test_4(4, Classification::Deficient);
        #[ignore]
        test_6(6, Classification::Perfect);
        #[ignore]
        test_12(12, Classification::Abundant);
        #[ignore]
        test_28(28, Classification::Perfect);
        #[ignore]
        test_30(30, Classification::Abundant);
        #[ignore]
        test_32(32, Classification::Deficient);
        #[ignore]
        test_33550335(33550335, Classification::Abundant);
        #[ignore]
        test_33550336(33550336, Classification::Perfect);
        #[ignore]
        test_33550337(33550337, Classification::Deficient);
    }
}

Desired behavior: this sed line removes only the text #[ignore] when encountered in the relevant files.