t2019: don't create unused files

Tests in t2019-checkout-ambiguous-ref.sh redirect two invocations of
"git checkout" to files "stdout" and "stderr".  Several assertions are
made using file "stderr".  File "stdout", however, is unused.

Don't redirect standard output of "git checkout" to file "stdout" in
t2019-checkout-ambiguous-ref.sh to avoid creating unnecessary files.

Signed-off-by: Andrei Rybak <rybak.a.v@gmail.com>
Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t2019-checkout-ambiguous-ref.sh

@@ -16,7 +16,7 @@ test_expect_success 'setup ambiguous refs' '
 '
 
 test_expect_success 'checkout ambiguous ref succeeds' '
-	git checkout ambiguity >stdout 2>stderr
+	git checkout ambiguity 2>stderr
 '
 
 test_expect_success 'checkout produces ambiguity warning' '
@@ -37,7 +37,7 @@ test_expect_success 'checkout reports switch to branch' '
 '
 
 test_expect_success 'checkout vague ref succeeds' '
-	git checkout vagueness >stdout 2>stderr &&
+	git checkout vagueness 2>stderr &&
 	test_set_prereq VAGUENESS_SUCCESS
 '