wic/direct.py: Avoid exception if using multiple rawcopy/no-table entries.
If we are both having a bootloader and a U-Boot environment file, we
can end up with two entries using "--source rawcopy" and "--no-table",
and since they reuse the same file [1], their cleanup handlers will
try to delete the same file twice. So make sure we only do it once.
[1] Although they reuse the same file, the resulting output is
correct, so it appears the file is accessed in properly sequential
order.
Signed-off-by: Kristian Amlie <kristian.amlie@mender.io> Signed-off-by: Ross Burton <ross.burton@intel.com>
