Failure to produce documentation with python3.11.

[emollier]

In Debian Bug#1027936, Adrian Bunk noticed that the documentation failed to be produced with python3.11 with the following symptom:

Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/sphinx/config.py", line 350, in eval_config_file
    exec(code, namespace)
  File "/<<PKGBUILDDIR>>/docs_sphinx/conf.py", line 71, in <module>
    generate_examples.main(root_dir, target_dir)
  File "/<<PKGBUILDDIR>>/debian/tmp/usr/lib/python3.11/dist-packages/brian2/sphinxext/generate_examples.py", line 72, in main
    with codecs.open(fname, 'rU', encoding='utf-8') as f:
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "<frozen codecs>", line 906, in open
ValueError: invalid mode: 'rUb'

This patch removes a couple of uses of unified newline "open" invocations, which have no effect since the first version of python3. This may cause changes of behavior with python2, but this interpreter is unmaintained since 2020.

Signed-off-by: Étienne Mollier emollier@debian.org

[mstimberg]

Many thanks for the report and fix. I was a bit surprised that we still had the U flags in there, since I thought that the pyupgrade tool had taken care of this. It turns out that it only did for open calls, not for codecs.open. I think we only used codecs.open here since we needed to enforce utf-8, but with modern Python versions, we can also do this with open. I therefore commited a change that gets rid of the use of codecs here. I also updated our test suite so that it tests building the HTML docs with the latest Python version – hopefully that should avoid this type of issue in the future. Thanks again, I'll go ahead with the merge as soon as the tests have passed.

[emollier]

Hi Marcel,
Great, glad this helped!
Have a nice day, :)
Étienne.