t1010-mktree: Adjust expected result to code and documentation

The last two tests here were always supposed to fail in the sense
that, according to code and documentation, mktree should read non-recursive
ls-tree output, but not recursive one, and therefore explicitely refuses
to deal with slashes.

Adjust the test (must_fail) so that it succeeds when mktree dies on
slashes.

Signed-off-by: Michael J Gruber <git@drmicha.warpmail.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t1010-mktree.sh

@@ -58,14 +58,12 @@ test_expect_success 'allow missing object with --missing' '
 	test_cmp tree.missing actual
 '
 
-test_expect_failure 'mktree reads ls-tree -r output (1)' '
-	git mktree <all >actual &&
-	test_cmp tree actual
+test_expect_success 'mktree refuses to read ls-tree -r output (1)' '
+	test_must_fail git mktree <all >actual
 '
 
-test_expect_failure 'mktree reads ls-tree -r output (2)' '
-	git mktree <all.withsub >actual &&
-	test_cmp tree.withsub actual
+test_expect_success 'mktree refuses to read ls-tree -r output (2)' '
+	test_must_fail git mktree <all.withsub >actual
 '
 
 test_done