Make sure that this path is intended for the salt master and trim it

def _check_proto(self, path):
        '''
        Make sure that this path is intended for the salt master and trim it
        '''
        if not path.startswith('salt://'):
            raise MinionError('Unsupported path: {0}'.format(path))
        file_path, saltenv = salt.utils.url.parse(path)
        return file_path