"unknown user root"?

[Yonatan Bokovza]

Hi all,
I'm seeing this same bento error for several of my
ports:
mtree: line 6: unknown user root

This happens at install time of ports where I use
do-install:
 ${INSTALL_SOMETHING} ${WRKSRC}/file ${PREFIX}/dir/file

This runs on my system as
install -c -o root -g wheel -m 123 /src/dir/file /dst/dir/file

I guess if there's no user "root", install will fail...
Is this a real problem, or just bento being weird?

Regards, 
Yonatan