Agreed, IPv6 would need 2xBIGINT, or alternatively DECIMAL(39,0) (http://www.koopman.me/2008/04/storing-ipv6-ips-in-mysql/)
Shouldn't this problem be adressed together with #1111?
Truncating the unsigned bigint to unsigned int should be minimal effort and we already have unit tests for the conversion to/from dotted decimal form. #1111 requires more effort.
(In ) fixes #1390 - use UNSIGNED INT for ip; since the upper 32 bits is unused, the ALTER statement simply truncates to the lower 32 bits