Issue #25406: Fixed a bug in C implementation of OrderedDict.move_to_end()

that caused segmentation fault or hang in iterating after moving several
items to the start of ordered dict.

diff --cc Lib/test/test_collections.py
Simple merge

diff --cc Misc/NEWS
index 312cde02c5f4f84abe728dd0bd4016c8b6781aa7,c0ea6e5d2015435a69c344dce1338d5f445d3478..dd6458dcdece6335d9276777b140c5d40fe6268d
--- 1/Misc/NEWS
--- 2/Misc/NEWS
+++ b/Misc/NEWS
@@@ -63,15 -45,10 +63,19 @@@ Core and Builtin
  Library
  -------
  
+ - Issue #25406: Fixed a bug in C implementation of OrderedDict.move_to_end()
+   that caused segmentation fault or hang in iterating after moving several
+   items to the start of ordered dict.
+ 
 +- Issue #25382: pickletools.dis() now outputs implicit memo index for the
 +  MEMOIZE opcode.
 +
 +- Issue #25357: Add an optional newline paramer to binascii.b2a_base64().
 +  base64.b64encode() uses it to avoid a memory copy.
 +
 +- Issue #24164: Objects that need calling ``__new__`` with keyword arguments,
 +  can now be pickled using pickle protocols older than protocol version 4.
 +
  - Issue #25364: zipfile now works in threads disabled builds.
  
  - Issue #25328: smtpd's SMTPChannel now correctly raises a ValueError if both