tests: add missing &&

Breaks in a test assertion's && chain can potentially hide
failures from earlier commands in the chain.

Commands intended to fail should be marked with !, test_must_fail, or
test_might_fail.  The examples in this patch do not require that.

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/t/t4027-diff-submodule.sh b/t/t4027-diff-submodule.sh
index d99814a..241a74d 100755
--- a/t/t4027-diff-submodule.sh
+++ b/t/t4027-diff-submodule.sh
@@ -316,11 +316,11 @@
 test_expect_success 'conflicted submodule setup' '
 
 	# 39 efs
-	c=fffffffffffffffffffffffffffffffffffffff
+	c=fffffffffffffffffffffffffffffffffffffff &&
 	(
-		echo "000000 $_z40 0	sub"
-		echo "160000 1$c 1	sub"
-		echo "160000 2$c 2	sub"
+		echo "000000 $_z40 0	sub" &&
+		echo "160000 1$c 1	sub" &&
+		echo "160000 2$c 2	sub" &&
 		echo "160000 3$c 3	sub"
 	) | git update-index --index-info &&
 	echo >expect.nosub '\''diff --cc sub