Adding a patch to support libusb and kernel usblp at the same time.
http://www.cups.org/str.php?L3357
The current Gentoo net-print/cups-1.4.6-r1 will fail if the kernel
is compiled with CONFIG_USB_PRINTER (either built-in or module,
see http://bugs.gentoo.org/show_bug.cgi?id=365627).
I have changed this error to a warning. However, the warning may
not be necessary with the patch applied.
Both Ubuntu and Debian have adopted this patch (other distros
have probably done likewise).
Please note: This Sabayon version of net-print/cups can be
obsoleted if/when the version in the main Gentoo tree adopts the
patch (I am pursuing pushing this patch back).