sphinxbase fails to build with Python 3.9.0a2.

/usr/bin/python3.9 ./doxy2swig.py -n xml/index.xml pydoc.i
parsing file: xml/cmd__ln_8h.xml
Traceback (most recent call last):
  File "/builddir/build/BUILD/sphinxbase-5prealpha/doc/./doxy2swig.py", line 488, in <module>
    main()
  File "/builddir/build/BUILD/sphinxbase-5prealpha/doc/./doxy2swig.py", line 484, in main
    convert(args[0], args[1], not options.func_def, options.quiet)
  File "/builddir/build/BUILD/sphinxbase-5prealpha/doc/./doxy2swig.py", line 463, in convert
    p.generate()
  File "/builddir/build/BUILD/sphinxbase-5prealpha/doc/./doxy2swig.py", line 123, in generate
    self.parse(self.xmldoc)
  File "/builddir/build/BUILD/sphinxbase-5prealpha/doc/./doxy2swig.py", line 132, in parse
    pm(node)
  File "/builddir/build/BUILD/sphinxbase-5prealpha/doc/./doxy2swig.py", line 162, in parse_Element
    handlerMethod(node)
  File "/builddir/build/BUILD/sphinxbase-5prealpha/doc/./doxy2swig.py", line 413, in do_doxygenindex
    p.generate()
  File "/builddir/build/BUILD/sphinxbase-5prealpha/doc/./doxy2swig.py", line 123, in generate
    self.parse(self.xmldoc)
  File "/builddir/build/BUILD/sphinxbase-5prealpha/doc/./doxy2swig.py", line 132, in parse
    pm(node)
  File "/builddir/build/BUILD/sphinxbase-5prealpha/doc/./doxy2swig.py", line 164, in parse_Element
    self.generic_parse(node)
  File "/builddir/build/BUILD/sphinxbase-5prealpha/doc/./doxy2swig.py", line 209, in generic_parse
    self.parse(n)
  File "/builddir/build/BUILD/sphinxbase-5prealpha/doc/./doxy2swig.py", line 132, in parse
    pm(node)
  File "/builddir/build/BUILD/sphinxbase-5prealpha/doc/./doxy2swig.py", line 162, in parse_Element
    handlerMethod(node)
  File "/builddir/build/BUILD/sphinxbase-5prealpha/doc/./doxy2swig.py", line 248, in do_compounddef
    self.parse(n)
  File "/builddir/build/BUILD/sphinxbase-5prealpha/doc/./doxy2swig.py", line 132, in parse
    pm(node)
  File "/builddir/build/BUILD/sphinxbase-5prealpha/doc/./doxy2swig.py", line 162, in parse_Element
    handlerMethod(node)
  File "/builddir/build/BUILD/sphinxbase-5prealpha/doc/./doxy2swig.py", line 356, in do_sectiondef
    self.generic_parse(node)
  File "/builddir/build/BUILD/sphinxbase-5prealpha/doc/./doxy2swig.py", line 209, in generic_parse
    self.parse(n)
  File "/builddir/build/BUILD/sphinxbase-5prealpha/doc/./doxy2swig.py", line 132, in parse
    pm(node)
  File "/builddir/build/BUILD/sphinxbase-5prealpha/doc/./doxy2swig.py", line 162, in parse_Element
    handlerMethod(node)
  File "/builddir/build/BUILD/sphinxbase-5prealpha/doc/./doxy2swig.py", line 302, in do_memberdef
    arg_type = n.getElementsByTagName('type')[0]
IndexError: list index out of range

For the build logs, see:
https://copr-be.cloud.fedoraproject.org/results/@python/python3.9/fedora-rawhide-x86_64/01170171-sphinxbase/

For all our attempts to build sphinxbase with Python 3.9, see:
https://copr.fedorainfracloud.org/coprs/g/python/python3.9/package/sphinxbase/

Testing and mass rebuild of packages is happening in copr. You can follow these instructions to test locally in mock if your package builds with Python 3.9:
https://copr.fedorainfracloud.org/coprs/g/python/python3.9/

Let us know here if you have any questions.

Python 3.9 will be included in Fedora 33. To make that update smoother, we're building Fedora packages with early pre-releases of Python 3.9.
A build failure prevents us from testing all dependent packages (transitive [Build]Requires), so if this package is required a lot, it's important for us to get it fixed soon.
We'd appreciate help from the people who know this package best, but if you don't want to work on this now, let us know so we can try to work around it on our side.