fetch-pack: avoid quadratic behavior in remove_duplicates

diff --git a/RelNotes b/RelNotes
index da6e81321a332fc7c7229c04e438f4161f27755d..bcb4fb98ff925389797125283e40c6e397efc1fd 120000 (symlink)
--- a/RelNotes
+++ b/RelNotes
@@ -1 +1 @@
-Documentation/RelNotes-1.6.1.2.txt
\ No newline at end of file
+Documentation/RelNotes/1.7.11.txt
\ No newline at end of file