Code:
make buildworld
make kernel
reboot -> single user model
mergemaster -p
make installworld
mergemaster [color="Red"](here, the system show me that many files need update)[/color]
System info: Freebsd 9.0 Release.
For a release version, the source code is static, if not security reason, nobody will modify anything. Even there are some security updates, these updates will not involve too many etc files. So, I think it is strange.