t6031-merge-recursive: More fixes for exec bit challenged filesystems

Commit 28f8802417 improved the tests to
work on filesystems that do not honor the exec bit, but it didn't go the
full nine yards: If chmod +x does not work, then test -x will not work
reliably, either, which was the only way how the tests checked the result.
This patch works around the issue by testing the index if the filesystem
does not report that the exec bit is set.

Signed-off-by: Johannes Sixt <j6t@kdbg.org>

t/t6031-merge-recursive.sh

@@ -20,7 +20,7 @@ test_expect_success 'mode change in one branch: keep changed version' '
 	git commit -m b1 &&
 	git checkout a1 &&
 	git merge-recursive master -- a1 b1 &&
-	test -x file1
+	{ test -x file1 || git ls-files -s file1 | grep ^100755; }
 '
 
 test_expect_success 'mode change in both branches: expect conflict' '
@@ -46,7 +46,7 @@ test_expect_success 'mode change in both branches: expect conflict' '
 		echo "100644 $H 3	file2"
 	) >expect &&
 	test_cmp actual expect &&
-	test -x file2
+	{ test -x file2 || git ls-files -s file2 | grep ^100755; }
 '
 
 test_done