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/t6040-tracking-info.sh b/t/t6040-tracking-info.sh
index 1785e17..1e0447f 100755
--- a/t/t6040-tracking-info.sh
+++ b/t/t6040-tracking-info.sh
@@ -60,7 +60,7 @@
 
 test_expect_success 'checkout with local tracked branch' '
 	git checkout master &&
-	git checkout follower >actual
+	git checkout follower >actual &&
 	grep "is ahead of" actual
 '