Historically, we have tried to up interfaces before running preup, so
that the kernel setups up the device and makes things like ethtool work
(some hardware cannot be correct probed until then). However this ends
up breaking other hardware, so a variable has been introduced to allow
the up prior to preup to be disabled: up_before_preup_IFVAR=no
X-Gentoo-Bug: 389475
X-Gentoo-Bug-URL: https://bugs.gentoo.org/show_bug.cgi?id=389475
Signed-off-by: Robin H. Johnson <robbat2@gentoo.org>