FreeBSD 6.1 source upgrade: Error code 1

[Mischa Peters]

After a new cvsup today, make buildworld now exists with the  
following message:

cd /usr/src; MAKEOBJDIRPREFIX=/usr/obj/usr/src/tmp  INSTALL="sh /usr/ 
src/tools/i
nstall.sh"  PATH=/usr/obj/usr/src/tmp/legacy/usr/sbin:/usr/obj/usr/ 
src/tmp/legac
y/usr/bin:/usr/obj/usr/src/tmp/legacy/usr/games:/sbin:/bin:/usr/sbin:/ 
usr/bin  W
ORLDTMP=/usr/obj/usr/src/tmp  MAKEFLAGS="-m /usr/src/tools/build/mk  - 
m /usr/src
/share/mk" /usr/obj/usr/src/make.i386/make -f Makefile.inc1   
DESTDIR=  BOOTSTRAP
PING=  -DNO_HTML -DNO_INFO -DNO_LINT -DNO_MAN -DNO_NLS -DNO_PIC  - 
DNO_PROFILE -D
NO_SHARED -DNO_CPU_CFLAGS -DNO_WARNS legacy
awk: syntax error at source line 1
context is
         /^#define[[:space:]]*__FreeBSD_version/ >>>  { <<<
"Makefile.inc1", line 101: warning: "awk '/^#define[[:space:]] 
*__FreeBSD_version
/ { print $3 }'  /usr/include/osreldate.h" returned non-zero status
ERROR: Source upgrades from versions prior to 5.3 not supported.
*** Error code 1

Stop in /usr/src.
*** Error code 1

Stop in /usr/src.
*** Error code 1

Stop in /usr/src.


This is a source upgrade of FreeBSD 6.1 and not a prior version to 5.3.

Any ideas?

Mischa