If any railroad or any part thereof, either completed or in course of construction, is sold under any trust deed, or upon the foreclosure of any mortgage thereon, or by any judicial sale, the parties acquiring title under such sale and their associates, successors, and assigns shall have and acquire and may exercise and enjoy the same rights, privileges, grants, franchises, immunities, and advantages enumerated in or conveyed by said trust deed or mortgage which belonged to and were enjoyed by the company making such deed or mortgage or contracting such debt, as far as the same relate or appertain to that portion of the road or the part or line thereof mentioned or described and conveyed by the mortgage or trust deed, and no further, as fully and absolutely in all respects as the railroad company, or the officers, shareholders, and agents of such company, might or could have had, had not such sale or purchase taken place, provided that nothing in this title shall be construed to reserve or authorize the conveyance of any exemption from taxation, either state, municipal, or county, or any special rights, privileges, and immunities that are not authorized by this title to be granted to all railroads alike, in conformity with the Constitution of Georgia.