Section 20A. In any city, town or other entity which accepts the provisions of this section, in a city, by a vote of the city council with the approval of the mayor; in a town, by a vote of the town meeting; in a municipality having a town council form of government, by a vote of the town council; and in any other entity having a retirement board subject to the provisions of this chapter, by a vote of the governing board of such entity, any civil action brought against a member of a retirement board, the defense or settlement of which action is made by an attorney employed by the retirement board, such member shall be indemnified for all expenses incurred in the defense thereof and shall be indemnified for damages to the same extent as provided for public employees in chapter two hundred and fifty-eight; provided, however, that the claim arose out of acts performed by such member or members while acting within the scope of his official duties; and provided, further, that no member of a retirement board shall be indemnified for expenses incurred in the defense of an action, or damages awarded in such action, in which there is shown to be a breach of fiduciary duty, an act of willful dishonesty or an intentional violation of law by such member.