options: adjust to behavior change in upstream _parse_optional

In Python 3.13 and 3.12.7, the behavior of _parse_optional has
changed. It used to raise an error on multiple matching actions
itself, and only ever return None or an option tuple. Now the
"raise error on multiple matching actions" code was moved out
into consume_optional, and _parse_optional returns either None
or a *list* of option tuples, which contains more than one if
multiple actions match. See:

python/cpython#124631
python/cpython#58573

This adapts to the change in a way that should work on both older
and newer Pythons.

Signed-off-by: Adam Williamson <awilliam@redhat.com>

pykickstart/options.py

@@ -177,9 +177,23 @@ def __init__(self, *args, **kwargs):
  self.lineno = None
 
  def _parse_optional(self, arg_string):
- option_tuple = ArgumentParser._parse_optional(self, arg_string)
+ # Before 3.13 and 3.12.7, this returned None or a single
+ # option tuple. From 3.13 / 3.12.7 onwards it returns None
+ # or a *list* of option tuples
+ option_tuple_or_tuples = ArgumentParser._parse_optional(self, arg_string)
+ # all we want to do here is a custom warning if the action is
+ # deprecated. we can only safely do this if there's exactly
+ # one matching action
+ if isinstance(option_tuple_or_tuples, list):
+ if len(option_tuple_or_tuples == 1):
+ option_tuple = option_tuple_or_tuples[0]
+ else:
+ return option_tuple_or_tuples
+ else:
+ option_tuple = option_tuple_or_tuples
+
  if option_tuple is None or option_tuple[0] is None:
- return option_tuple
+ return option_tuple_or_tuples
 
  action = option_tuple[0]
  option = action.option_strings[0]
@@ -191,7 +205,7 @@ def _parse_optional(self, arg_string):
  "kickstart. Please modify your kickstart file to remove this option.")
  % {"lineno": self.lineno, "option": option}, KickstartDeprecationWarning)
 
- return option_tuple
+ return option_tuple_or_tuples
 
  def add_argument(self, *args, **kwargs):
  if "introduced" in kwargs: