Issue #21905: Avoid RuntimeError in pickle.whichmodule() when sys.modules is mutated...

Patch by Olivier Grisel.

diff --cc Misc/ACKS
Simple merge

diff --cc Misc/NEWS
index 9e7efb9dfee60e6a1045f9b9fdbbc8c10d2f6def,6112a008e9eddb17cabf8cd5c457dd4c544b17dc..6b8ef3ec0144e9e05f24fe9f1d33599b0b034f3e
--- 1/Misc/NEWS
--- 2/Misc/NEWS
+++ b/Misc/NEWS
@@@ -162,36 -66,6 +162,39 @@@ Core and Builtin
  Library
  -------
  
++- Issue #21905: Avoid RuntimeError in pickle.whichmodule() when sys.modules
++  is mutated while iterating.  Patch by Olivier Grisel.
++
 +- Issue #11271: concurrent.futures.Executor.map() now takes a *chunksize*
 +  argument to allow batching of tasks in child processes and improve
 +  performance of ProcessPoolExecutor.  Patch by Dan O'Reilly.
 +
 +- Issue #21883: os.path.join() and os.path.relpath() now raise a TypeError with
 +  more helpful error message for unsupported or mismatched types of arguments.
 +
 +- Issue #22219: The zipfile module CLI now adds entries for directories
 +  (including empty directories) in ZIP file.
 +
 +- Issue #22449: In the ssl.SSLContext.load_default_certs, consult the
 +  enviromental variables SSL_CERT_DIR and SSL_CERT_FILE on Windows.
 +
 +- Issue #22508: The email.__version__ variable has been removed; the email
 +  code is no longer shipped separately from the stdlib, and __version__
 +  hasn't been updated in several releases.
 +
 +- Issue #20076: Added non derived UTF-8 aliases to locale aliases table.
 +
 +- Issue #20079: Added locales supported in glibc 2.18 to locale alias table.
 +
 +- Issue #20218: Added convenience methods read_text/write_text and read_bytes/
 +  write_bytes to pathlib.Path objects.
 +
 +- Issue #22437: Number of capturing groups in regular expression is no longer
 +  limited by 100.
 +
 +- Issue #17442: InteractiveInterpreter now displays the full chained traceback
 +  in its showtraceback method, to match the built in interactive interpreter.
 +
  - Issue #10510: distutils register and upload methods now use HTML standards
    compliant CRLF line endings.