current version of FreeBSD, this isn't guarenteed by the API. Custom
security modules, or future implementations of the setuid and setgid
may fail.
PR: bin/172289
PR: bin/172290
PR: bin/172291
Submittud by: Erik Cederstrand <erik@cederstrand.dk>
Discussed by: freebsd-security
Approved by: cperciva
MFC after: 1 week
