Section 4. No person shall be held to answer as a trustee in an action in a district court, except as provided in section fifty-four of chapter two hundred and eighteen, in any county other than that where he dwells or has a usual place of business; and if a person summoned as trustee in such court is out of the county at the time of the service of the trustee summons upon him, and does not return before final judgment in the action, he shall not be chargeable as trustee.