Get a version matcher for a requirement.
        :param reqt: The requirement
        :type reqt: str
        :return: A version matcher (an instance of
                 :class:`distlib.version.Matcher`).

def get_matcher(self, reqt):
        """
        Get a version matcher for a requirement.
        :param reqt: The requirement
        :type reqt: str
        :return: A version matcher (an instance of
                 :class:`distlib.version.Matcher`).
        """
        try:
            matcher = self.scheme.matcher(reqt)
        except UnsupportedVersionError:  # pragma: no cover
            # XXX compat-mode if cannot read the version
            name = reqt.split()[0]
            matcher = self.scheme.matcher(name)
        return matcher