When we intercepted the file download to a temp file, we broke the
exist/size checks which need to happen before the rename. Correct
the ordering.
For some reason, python 3.12 exposes this problem in the selftests
differently to previous versions.
(Bitbake rev: c56bd9a9280378bc64c6a7fe6d7b70847e0b9e6d)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>