BTW there are test regressions with expat 2.4.5, apparently due to some test snippets now being rejected as invalid XML:

======================================================================
ERROR: test_issue3151 (test.test_xml_etree.BugsTest)
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Traceback (most recent call last):
  File "/home/mgorny/git/cpython/Lib/xml/etree/ElementTree.py", line 1718, in feed
    self.parser.Parse(data, False)
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
xml.parsers.expat.ExpatError: syntax error: line 1, column 0

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/mgorny/git/cpython/Lib/test/test_xml_etree.py", line 2196, in test_issue3151
    e = ET.XML('<prefix:localname xmlns:prefix="${stuff}"/>')
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/mgorny/git/cpython/Lib/xml/etree/ElementTree.py", line 1347, in XML
    parser.feed(text)
    ^^^^^^^^^^^^^^^^^
  File "/home/mgorny/git/cpython/Lib/xml/etree/ElementTree.py", line 1720, in feed
    self._raiseerror(v)
    ^^^^^^^^^^^^^^^^^^^
  File "/home/mgorny/git/cpython/Lib/xml/etree/ElementTree.py", line 1627, in _raiseerror
    raise err
    ^^^^^^^^^
xml.etree.ElementTree.ParseError: syntax error: line 1, column 0


======================================================================
ERROR: testEncodings (test.test_minidom.MinidomTest)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/mgorny/git/cpython/Lib/test/test_minidom.py", line 1150, in testEncodings
    self.assertRaises(UnicodeDecodeError, parseString,
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/mgorny/git/cpython/Lib/unittest/case.py", line 734, in assertRaises
    return context.handle('assertRaises', args, kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/mgorny/git/cpython/Lib/unittest/case.py", line 218, in handle
    callable_obj(*args, **kwargs)
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/mgorny/git/cpython/Lib/xml/dom/minidom.py", line 1998, in parseString
    return expatbuilder.parseString(string)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/mgorny/git/cpython/Lib/xml/dom/expatbuilder.py", line 925, in parseString
    return builder.parseString(string)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/mgorny/git/cpython/Lib/xml/dom/expatbuilder.py", line 223, in parseString
    parser.Parse(string, True)
    ^^^^^^^^^^^^^^^^^^^^^^^^^^
xml.parsers.expat.ExpatError: not well-formed (invalid token): line 1, column 5

======================================================================
ERROR: testExceptionOnSpacesInXMLNSValue (test.test_minidom.MinidomTest)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/mgorny/git/cpython/Lib/test/test_minidom.py", line 1613, in testExceptionOnSpacesInXMLNSValue
    parseString('<element xmlns:abc="http:abc.com/de f g/hi/j k"><abc:foo /></element>')
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/mgorny/git/cpython/Lib/xml/dom/minidom.py", line 1998, in parseString
    return expatbuilder.parseString(string)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/mgorny/git/cpython/Lib/xml/dom/expatbuilder.py", line 925, in parseString
    return builder.parseString(string)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/mgorny/git/cpython/Lib/xml/dom/expatbuilder.py", line 223, in parseString
    parser.Parse(string, True)
    ^^^^^^^^^^^^^^^^^^^^^^^^^^
xml.parsers.expat.ExpatError: syntax error: line 1, column 0