Fix refs appearing in dupes-only view

[glubsy]

• Some refs appeared in the dupes-only view after a re-prioritization was done a second time.
• It seems the core.Results.__dupes list was not properly updated whenever core.app.Dupeguru.reprioritize_groups() -> core.Results.sort_dupes() was called.
  When a re-prioritization is done, some refs became dupe, and some dupes became ref in their place. So we need to update the new state of the internal list of dupes kept by the Results object, instead of relying on the outdated cached one.
• Fix Dupes Only view is not updated after Re-Prioritize Results #757.

[arsenetar]

Issue with this change seems to come from the sort_dupes() and __get_dupe_list() calling each other recursively, due to __get_dupe_list no longer having the blocking conditional on line 97.

[arsenetar]

I just did a quick test splitting out sort_dupes() into two functions as below:

    def sort_dupes(self, key, asc=True, delta=False):
        """Sort :attr:`dupes` according to ``key``.

        :param str key: key attribute name to sort with.
        :param bool asc: If false, sorting is reversed.
        :param bool delta: If true, sorting occurs using :ref:`delta values <deltavalues>`.
        """
        if not self.__dupes:
            self.__get_dupe_list()
        self.__sort_dupes(key, asc, delta)

    def __sort_dupes(self, key, asc, delta):
        keyfunc = lambda d: self.app._get_dupe_sort_key(
            d, lambda: self.get_group_of_duplicate(d), key, delta
        )
        self.__dupes.sort(key=keyfunc, reverse=not asc)
        self.__dupes_sort_descriptor = (key, asc, delta)

I changed the __get_dupe_list() to call the __sort_dupes() function directly. With that it seems only the "cached results list" test fails.

[glubsy]

Ah well, I did it slightly differently and the caching works just like before. The cache only gets updated whenever a group has changed.

[arsenetar]

Yeah I was just trying to verify that was the primary issue, I think the way you fixed it is better and keeps the "cached results" working.