[3.9] bpo-33187: Document 3.9 changes to xml.etree.ElementInclude.include (GH-20438) by miss-islington · Pull Request #20722 · python/cpython

@hauntsaninja @miss-islington

…ythonGH-20438)

Looks like the merging of bpo-33187 and bpo-20928 was racy, resulting in
this change going undocumented.
(cherry picked from commit 301f0d4)

Co-authored-by: Shantanu <hauntsaninja@users.noreply.github.com>