def load(self, requirements_file=None):
        """Load or reload requirements from a requirements.txt file.

        :param requirements_file: if not given, the filename used from
            initialization will be read again.
        """
        if requirements_file is None:
            requirements_file = self.filename
            if requirements_file is None:
                raise ValueError("no filename provided")
        elif isinstance(requirements_file, text_type):
            requirements_file = Path(requirements_file)
        self.clear()
        with requirements_file.open() as f:
            self.loads(f.read())

        if isinstance(requirements_file, (text_type, Path)):
            self.filename = requirements_file
def db_version(engine, abs_path, init_version):
    """Show the current version of the repository.

    :param engine:  SQLAlchemy engine instance for a given database
    :param abs_path: Absolute path to migrate repository
    :param version:  Initial database version
    """
    repository = _find_migrate_repo(abs_path)
    try:
        return versioning_api.db_version(engine, repository)
    except versioning_exceptions.DatabaseNotControlledError:
        meta = sqlalchemy.MetaData()
        meta.reflect(bind=engine)
        tables = meta.tables
        if len(tables) == 0 or 'alembic_version' in tables:
            db_version_control(engine, abs_path, version=init_version)
            return versioning_api.db_version(engine, repository)
        else:
            raise exception.DbMigrationError(
                message=_(
                    "The database is not under version control, but has "
                    "tables. Please stamp the current version of the schema "
                    "manually."))