The restriction imposed upon the Mississippi Transportation Commission and the boards of supervisors of the several counties in the employment of labor to work and maintain the state highways and the public roads of the several supervisors' districts of the county, as provided in Section 23-15-881, shall not apply to road contractors or bridge contractors engaged in the construction or maintenance of state highways or county roads under contracts awarded by the Mississippi Transportation Commission, or the board of supervisors, as the case may be, where such contracts shall have been awarded to the lowest responsible bidder, after legal advertisement, as provided by law; nor shall the restriction imposed in Section 23-15-881 apply to the labor employed by such road contractors or bridge contractors in carrying out such contracts. Nor shall the provisions of this chapter apply to the employment by the Mississippi Transportation Commission, or the board of supervisors, as the case may be, of extra labor employed to make repairs upon the state highways or highway bridges, or upon the county roads or bridges, in cases where such state highways or highway bridges, or such county roads or bridges, have been damaged or destroyed by severe storms, floods or other unforeseen disasters.