Commit e6a6d307 detected complete part files by comparing a payload's
max_size to initial_size. However, these values are also equal when we
use pacman -U on a URL as max_size is set to 0 in that case. Add a further
condition to avoid that.
Signed-off-by: Allan McRae <allan@archlinux.org>
(cherry picked from commit e54617c7d5)
d61c398b2c