fetch2/wget: Check downloaded file isn't zero size

I can't think of a reason we'd download zero sized files however there are
reasons zero length files can accidently make it onto source mirrors.

This check allows us to ignore the broken files and switch to another
mirror rather than fail with odd checksum failures.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
runqueue: Only attempt to print closest matching task if there is a match

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>