contrib/examples/git-clone.sh: avoid "test <cond> -a/-o <cond>"

The construct is error-prone; "test" being built-in in most modern
shells, the reason to avoid "test <cond> && test <cond>" spawning
one extra process by using a single "test <cond> -a <cond>" no
longer exists.

Signed-off-by: Elia Pinto <gitter.spiros@gmail.com>
Reviewed-by: Matthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

contrib/examples/git-clone.sh

@@ -516,7 +516,7 @@ then
 
 	case "$no_checkout" in
 	'')
-		test "z$quiet" = z -a "z$no_progress" = z && v=-v || v=
+		test "z$quiet" = z && test "z$no_progress" = z && v=-v || v=
 		git read-tree -m -u $v HEAD HEAD
 	esac
 fi