Could this be bug #149790 ?
I don't think so- my NFS server has a proper DNS entry and I'm seeing
different error messages.
I'm having the same problem (see message: FC4t1: Can't install form isos
via nfs...). One of the consoles reports that it has mounted my nfs
volume on /mnt/source, but says: "LOOP_FD_SET Failed: device or resource
busy" when it tries to mount the isos on loopback.
-Ed