make buildworld failed

[Marcin Jessa]

Tried to run make buildworld on sources updated a few mins ago:

/usr/obj/usr/src/sbin/ipf/libipf created for /usr/src/sbin/ipf/libipf
===> sbin/ipf/ipf (obj)
mkdir: /usr/obj/usr/src/sbin/ipf/ipf: File exists
*** Error code 1

The script seems to try to create a dir in place of exiting binary:

# ls -l /usr/obj/usr/src/sbin/ipf/ipf
-rwxr-xr-x  1 root  wheel  41595 May 14 21:52 /usr/obj/usr/src/sbin/ipf/ipf