bpo-24538: Fix bug in shutil involving the copying of xattrs to read-only files. (PR-13212)

Extended attributes can only be set on user-writeable files, but shutil previously
first chmod()ed the destination file to the source's permissions and then tried to
copy xattrs. This will cause failures if attempting to copy read-only files with
xattrs, as occurs with Git clones on Lustre FS.
diff --git a/Misc/ACKS b/Misc/ACKS
index 300e788..dfb9637 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -149,6 +149,7 @@
 Ron Bickers
 Natalia B. Bidart
 Adrian von Bidder
+Olexa Bilaniuk
 David Binger
 Dominic Binks
 Philippe Biondi