So when upgrading a FreeBSD install via make world you really should read UPDATING first.
Especially when upgrading to a version of the OS that adds a new system call.
You do not want to install a set of userland tools that require said system call without first installing a kernel that supports it.
Figuring out how to install the kernel without working make and ls commands was fun.
At least I had already built the new kernel, so I didn't have to scramble to find a bootable rescue CD...
This is totally why I am not a sysadmin.