Index generation error - "/a/ports/lang/php4" (?) non-existent

[Radek Kozlowski]

root at bonzo:/usr/sup# portsdb -Uu
Updating the ports index ... Generating INDEX.tmp - please 
wait..pear-Archive_Tar-1.2: "/a/ports/lang/php4" non-existent -- 
dependency list incomplete
===> archivers/pear-Archive_Tar failed
*** Error code 1
1 error

root at bonzo:/usr/sup# uname -v
FreeBSD 5.2-CURRENT #65: Tue Jun 15 01:44:27 CEST 2004 
root at bonzo:/usr/obj/usr/src/sys/BONZO

The ports tree is complete and up-to-date. I have no idea where this 
'/a/ports/' is coming from. I didn't find anything suspicious in the 
Makefiles nor in /etc/make.conf. I even tried cvsuping everything from 
the beginning, but that didn't help much. What could it be?

Thanks,

-Radek