unpack-trees.c: use path_excluded() in check_ok_to_remove()

diff --git a/RelNotes b/RelNotes
index 81eb3c2271e534c04ec65227b45da12ab6eccf77..b5c2795d47322706288f8683a87d6cd1c9c9833e 120000 (symlink)
--- a/RelNotes
+++ b/RelNotes
@@ -1 +1 @@
-Documentation/RelNotes/1.7.7.7.txt
\ No newline at end of file
+Documentation/RelNotes/1.7.8.6.txt
\ No newline at end of file