contrib/examples/git-repack.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-repack.sh

@@ -76,8 +76,8 @@ case ",$all_into_one," in
 				existing="$existing $e"
 			fi
 		done
-		if test -n "$existing" -a -n "$unpack_unreachable" -a \
-			-n "$remove_redundant"
+		if test -n "$existing" && test -n "$unpack_unreachable" && \
+			test -n "$remove_redundant"
 		then
 			# This may have arbitrary user arguments, so we
 			# have to protect it against whitespace splitting