CPUTYPE weirdness

[Pascal Hofstee]

Hi,

I just installed a fresh FreeBSD/amd64 7.0-RELEASE and trying to update
to RELENG_7_0.

I added CPUTYPE ?= core2 to my /etc/src.conf and every call to make
in /usr/src now gives me the error

"/usr/src/Makefile.inc1", line 142: CPUTYPE global should be set
with ?=.
*** Error code 1

Anyone has any idea what i am doing wrong here ... this same mechanism
has worked flawlessly on several other systems (although they were not
RELENG_7_0) ?

-- 
  Pascal Hofstee