Regression in new bisect implementation in cargo-msrv v0.14.0

[foresterre]

    use super::Bisect;
    use crate::check::Check;
    use crate::outcome::{Outcome, SuccessOutcome};
    use crate::reporter::no_output::NoOutput;
    use crate::search_methods::FindMinimalCapableToolchain;
    use crate::semver::Version;
    use crate::toolchain::{OwnedToolchainSpec, ToolchainSpec};
    use crate::{semver, Config, ModeIntent, TResult};
    use rust_releases::Release;

    struct FakeRunner;

    impl Check for FakeRunner {
        fn check(&self, config: &Config, toolchain: &ToolchainSpec) -> TResult<Outcome> {
            Ok(Outcome::Success(SuccessOutcome {
                toolchain_spec: OwnedToolchainSpec::new(toolchain.version(), config.target()),
            }))
        }
    }

    fn fake_config() -> Config<'static> {
        Config::new(ModeIntent::Find, "".to_string())
    }

    #[test]
    fn all_are_valid() {
        let search_space = vec![
            Release::new_stable(semver::Version::new(1, 58, 1)),
            Release::new_stable(semver::Version::new(1, 57, 0)),
            Release::new_stable(semver::Version::new(1, 56, 1)),
        ];

        let bisect = Bisect::new(FakeRunner {});

        let result = bisect
            .find_toolchain(&search_space, &fake_config(), &NoOutput {})
            .unwrap();

        assert_eq!(result.unwrap_version(), Version::new(1, 56, 1));
    }

Actual result: Version::new(1, 57, 0)
Expected result: Version::new(1, 56, 1)

The reason for this result is that the indices left == right which causes the algorithm to stop. In this case, we'd like to go one step further, since we want to go beyond an insertion point.