buildworld fails: fatal error: 'netpfil/pf/pf.h' file not found

Hello!

For several days buildworld fails for me with the following error. Cleaning and
rebuilding didn't help.

===> tests/sys/netpfil/pf/ioctl (all)
--- validation ---
(cd /usr/src/tests/sys/netpfil/pf/ioctl &&  DEPENDFILE=.depend.validation  NO_SUBDIR=1 make -f /usr/src/tests/sys/netpfil/pf/ioctl/Makefile _RECURSING_PROGS=t  PROG=validation )
Building /home/obj/usr/src/amd64.amd64/tests/sys/netpfil/pf/ioctl/validation.o
--- validation.o ---
In file included from /usr/src/tests/sys/netpfil/pf/ioctl/validation.c:35:
/home/obj/usr/src/amd64.amd64/tmp/usr/include/net/pfvar.h:49:10: fatal error: 'netpfil/pf/pf.h' file not found
#include <netpfil/pf/pf.h>
         ^~~~~~~~~~~~~~~~~
1 error generated.
*** [validation.o] Error code 1

make[8]: stopped in /usr/src/tests/sys/netpfil/pf/ioctl


My /etc/src.conf (I have PF switched off):
WITHOUT_ACCT=
WITHOUT_AMD=
WITHOUT_APM=
WITHOUT_ATM=
WITHOUT_AUTHPF=
WITHOUT_BLACKLIST=
WITHOUT_BLUETOOTH=
WITHOUT_BOOTPARAMD=
WITHOUT_BOOTPD=
WITHOUT_BSNMP=
WITHOUT_CCD=
WITHOUT_CROSS_COMPILER=
WITHOUT_CTM=
WITHOUT_CUSE=
WITHOUT_CXGBETOOL=
# WITHOUT_DEBUG_FILES=
WITHOUT_EE=
WITHOUT_FDT=
WITHOUT_FINGER=
WITHOUT_FLOPPY=
WITHOUT_FREEBSD_UPDATE=
WITHOUT_FTP=
WITHOUT_GDB=
WITHOUT_GNU_GREP_COMPAT=
WITHOUT_HAST=
WITHOUT_HTML=
WITHOUT_HYPERV=
WITHOUT_IPFILTER=
WITHOUT_ISCSI=
WITHOUT_KVM=
WITHOUT_LEGACY_CONSOLE=
WITHOUT_LIB32=
WITHOUT_LPR=
WITHOUT_NDIS=
WITHOUT_PC_SYSINSTALL=
WITHOUT_PF=
WITHOUT_PPP=
WITHOUT_QUOTAS=
WITHOUT_RADIUS_SUPPORT=
WITHOUT_RBOOTD=
WITHOUT_SHAREDOCS=
WITHOUT_TALK=
WITHOUT_TFTP=
WITHOUT_TIMED=

WITH_BSD_GREP=
WITH_CCACHE_BUILD=
# WITH_CLANG_EXTRAS=
# WITH_CTF=
# WITH_DTRACE_TESTS=
WITH_SORT_THREADS=
WITH_SVN=

-- 
Regards,                 | "In theory there is no difference between theory
  Vladimir Zakharov      | and practice. In practice there is."- Yogi Berra