Retrieve configuration for a given repository.

        Args:
            repo (str): a repository "realm" (alias) or its URL

        Returns:
            RepositoryConfig: if there is configuration for that repository
            None: otherwise

def get_repo_config(self, repo='default'):
        """Retrieve configuration for a given repository.

        Args:
            repo (str): a repository "realm" (alias) or its URL

        Returns:
            RepositoryConfig: if there is configuration for that repository
            None: otherwise
        """
        for repo_config in self.repositories:
            if repo_config.name == repo or repo_config.url in RepositoryURL(repo):
                return repo_config

        return None