Remove now unused patch for Python 3.8 fix

python38_fix.patch

@@ -1,80 +0,0 @@
-diff --git a/synapse/util/caches/descriptors.py b/synapse/util/caches/descriptors.py
-index 5ac2530a6..d803d62b8 100644
---- a/synapse/util/caches/descriptors.py
-+++ b/synapse/util/caches/descriptors.py
-@@ -17,8 +17,8 @@ import functools
- import inspect
- import logging
- import threading
--from collections import namedtuple
--from typing import Any, cast
-+from typing import Any, Tuple, Union, cast
-+from weakref import WeakValueDictionary
- 
- from six import itervalues
- 
-@@ -38,6 +38,8 @@ from . import register_cache
- 
- logger = logging.getLogger(__name__)
- 
-+CacheKey = Union[Tuple, Any]
-+
- 
- class _CachedFunction(Protocol):
-     invalidate = None  # type: Any
-@@ -430,7 +432,7 @@ class CacheDescriptor(_CacheDescriptorBase):
-             # Add our own `cache_context` to argument list if the wrapped function
-             # has asked for one
-             if self.add_cache_context:
--                kwargs["cache_context"] = _CacheContext(cache, cache_key)
-+                kwargs["cache_context"] = _CacheContext.get_instance(cache, cache_key)
- 
-             try:
-                 cached_result_d = cache.get(cache_key, callback=invalidate_callback)
-@@ -625,14 +627,38 @@ class CacheListDescriptor(_CacheDescriptorBase):
-         return wrapped
- 
- 
--class _CacheContext(namedtuple("_CacheContext", ("cache", "key"))):
--    # We rely on _CacheContext implementing __eq__ and __hash__ sensibly,
--    # which namedtuple does for us (i.e. two _CacheContext are the same if
--    # their caches and keys match). This is important in particular to
--    # dedupe when we add callbacks to lru cache nodes, otherwise the number
--    # of callbacks would grow.
--    def invalidate(self):
--        self.cache.invalidate(self.key)
-+class _CacheContext:
-+    """Holds cache information from the cached function higher in the calling order.
-+
-+    Can be used to invalidate the higher level cache entry if something changes
-+    on a lower level.
-+    """
-+
-+    _cache_context_objects = (
-+        WeakValueDictionary()
-+    )  # type: WeakValueDictionary[Tuple[Cache, CacheKey], _CacheContext]
-+
-+    def __init__(self, cache, cache_key):  # type: (Cache, CacheKey) -> None
-+        self._cache = cache
-+        self._cache_key = cache_key
-+
-+    def invalidate(self):  # type: () -> None
-+        """Invalidates the cache entry referred to by the context."""
-+        self._cache.invalidate(self._cache_key)
-+
-+    @classmethod
-+    def get_instance(cls, cache, cache_key):  # type: (Cache, CacheKey) -> _CacheContext
-+        """Returns an instance constructed with the given arguments.
-+
-+        A new instance is only created if none already exists.
-+        """
-+
-+        # We make sure there are no identical _CacheContext instances. This is
-+        # important in particular to dedupe when we add callbacks to lru cache
-+        # nodes, otherwise the number of callbacks would grow.
-+        return cls._cache_context_objects.setdefault(
-+            (cache, cache_key), cls(cache, cache_key)
-+        )
- 
- 
- def cached(