checkout test: enable test with complex relative path

This test was added, commented out, in fed1b5ca (git-checkout: Test
for relative path use, 2007-11-09).  Later git's path handling was
improved (d089ebaa, setup: sanitize absolute and funny paths in
get_pathspec(), 2008-01-28) but we forgot to enable the now-working
test.

This test expects to run from a subdirectory, so add a 'cd'.  While
we're here, examine the content of the checked-out file instead of
just checking that it exists.  The other checkout tests already do the
same.

Signed-off-by: Stefan Beller <stefanbeller@googlemail.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>

t/t2008-checkout-subdir.sh

@@ -58,13 +58,13 @@ test_expect_success 'checkout with simple prefix' '
 
 '
 
-# This is not expected to work as ls-files was not designed
-# to deal with such.  Enable it when ls-files is updated.
-: test_expect_success 'checkout with complex relative path' '
-
-	rm file1 &&
-	git checkout HEAD -- ../dir1/../dir1/file1 && test -f ./file1
-
+test_expect_success 'checkout with complex relative path' '
+	(
+		cd dir1 &&
+		rm file1 &&
+		git checkout HEAD -- ../dir1/../dir1/file1 &&
+		test "hello" = "$(cat file1)"
+	)
 '
 
 test_expect_success 'relative path outside tree should fail' \