Find a version in pyenv from the version supplied.

        A ValueError is raised if a matching version cannot be found.

def find_version_to_install(self, name):
        """Find a version in pyenv from the version supplied.

        A ValueError is raised if a matching version cannot be found.
        """
        version = Version.parse(name)
        if version.patch is not None:
            return name
        try:
            best_match = max((
                inst_version
                for inst_version in self.iter_installable_versions()
                if inst_version.matches_minor(version)
            ), key=operator.attrgetter('cmpkey'))
        except ValueError:
            raise ValueError(
                'no installable version found for {0!r}'.format(name),
            )
        return best_match