download.sh: consisten lazy evaluation in checks
download.sh: consisten lazy evaluation in checks

Use && rather than -a so second expression is not evaluated
if first does not match.

Signed-off-by: Michael Adam <dcf2bf3ff8ea93047d51252815aac9756207ea09@samba.org>

sephii/vagrant-lxc-base-boxes,DavBfr/vagrant-lxc-base-boxes,DavBfr/vagrant-lxc-base-boxes,obnoxxx/vagrant-lxc-base-boxes