let version = env::var("RADICLE_VERSION").unwrap_or_else(|_| {

        // If `RADICLE_VERSION` is not set, we still try our best to

        // describe this version by asking git. The result will in many

        // cases be a reference to the last released version, and how

        // many commits we are ahead, plus a short version of the

        // object ID of `HEAD`, e.g. `releases/x.y.z-80-gefe10f95be-dirty`

        // which would mean that we built 80 commits ahead of release

        // x.y.z, with efe10f95be being a unique prefix of the OID of

        // `HEAD`, and the working directory was dirty.

        // If this is a build pointing to a commit that has release tag, this

        // will just return the tag name itelf, e.g. `releases/x.y.z`.

        // If all fails, we just use `hash`, which, in the worst case is

        // still "unknown" (see above) but in most cases will just be

        // the short OID of `HEAD`.

        Command::new("git")

            .arg("describe")

            .arg("--always")

            .arg("--broken")

            .arg("--dirty")

            .output()

            .ok()

            .and_then(|output| {

                if output.status.success() {

                    String::from_utf8(output.stdout).ok()

                } else {

                    None

                }

            })

            .unwrap_or(hash.clone())

    });

    // Since in the previous step we are likely to almost always end up with

    // a prefix of `releases/`, as this is the scheme we use in this

    // repository, we remove this common prefix, to get nice version numbers.

    let version = if let Some(stripped) = version.strip_prefix("releases/") {

        stripped.to_owned()

        version