Resolve a relative url to the  appropriate realm name.

def getDomainRealm(self, inputURL, environ):
        """Resolve a relative url to the  appropriate realm name."""
        # we don't get the realm here, its already been resolved in
        # request_resolver
        if inputURL.startswith("/"):
            inputURL = inputURL[1:]
        parts = inputURL.split("/")
        return parts[0]