`[\?]` fails to parse in `Loader` but works in `CLoader`

[silverwind]

The string [\?] parses fine in CLoader while Loader fails to do so. Is it expected?

$ python3
Python 3.11.5 (main, Aug 24 2023, 15:18:16) [Clang 14.0.3 (clang-1403.0.22.14.1)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from yaml import load, CLoader, Loader
>>> load('[\?]', CLoader)
['\\?']
>>> load('[\?]', Loader)
...
  File "/usr/local/lib/python3.11/site-packages/yaml/parser.py", line 98, in check_event
    self.current_event = self.state()
                         ^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/yaml/parser.py", line 483, in parse_flow_sequence_entry
    raise ParserError("while parsing a flow sequence", self.marks[-1],
yaml.parser.ParserError: while parsing a flow sequence
  in "<unicode string>", line 1, column 1:
    [\?]
    ^
expected ',' or ']', but got '?'
  in "<unicode string>", line 1, column 3:
    [\?]
      ^

[perlpunk]

duplicate of #128

[silverwind]

Okay, but shouldn't both loaders either fail or succeed in tandem?

[perlpunk]

Ideally, yes, but it has to be implemented in both libyaml and pyyaml. First, the maintainers of pyyaml should be clear if they want that fix or not