Since xml.etree.cElementTree does not exist in Python 3.9, the statement that it's deprecated should be removed from the documentation.

I will clean this

This issue looks like the same with https://bugs.python.org/issue40064

Same core problem (module removed with insufficient document update), but a different action is needed for 3.8 and 3.9.

When I started testing an application with 3.9 and found one of the dependencies broken because it was relying directly on xml.etree.cElementTree, I had to dig into the history to determine that it was removed intentionally.  Updated documentation would have helped.

I did file an issue on the dependency as well:
https://github.com/boto/botocore/issues/2002

Thank you for catching this Fred. I am surprised that some code uses xml.etree.cElementTree without falling back to xml.etree.ElementTree. In Python 3 you can just use xml.etree.ElementTree, in Python 2 you have to fallback to the Python implementation because the C implementation was optional.

The common idiom is

try:
    import xml.etree.cElementTree as ET
except ImportError:
    import xml.etree.ElementTree as ET

The Python 2.7 documentation was not clear that xml.etree.cElementTree was optional, so users who didn't dive into the implementation or build process could easily not have known unless someone with a more limited installation used their code.