--- a/mercurial/thirdparty/jaraco/collections.py	Mon May 29 18:41:58 2023 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,56 +0,0 @@
-# adapted from jaraco.collections 3.9
-
-import collections
-
-
-class Projection(collections.abc.Mapping):
-    """
-    Project a set of keys over a mapping
-
-    >>> sample = {'a': 1, 'b': 2, 'c': 3}
-    >>> prj = Projection(['a', 'c', 'd'], sample)
-    >>> prj == {'a': 1, 'c': 3}
-    True
-
-    Keys should only appear if they were specified and exist in the space.
-
-    >>> sorted(list(prj.keys()))
-    ['a', 'c']
-
-    Attempting to access a key not in the projection
-    results in a KeyError.
-
-    >>> prj['b']
-    Traceback (most recent call last):
-    ...
-    KeyError: 'b'
-
-    Use the projection to update another dict.
-
-    >>> target = {'a': 2, 'b': 2}
-    >>> target.update(prj)
-    >>> target == {'a': 1, 'b': 2, 'c': 3}
-    True
-
-    Also note that Projection keeps a reference to the original dict, so
-    if you modify the original dict, that could modify the Projection.
-
-    >>> del sample['a']
-    >>> dict(prj)
-    {'c': 3}
-    """
-
-    def __init__(self, keys, space):
-        self._keys = tuple(keys)
-        self._space = space
-
-    def __getitem__(self, key):
-        if key not in self._keys:
-            raise KeyError(key)
-        return self._space[key]
-
-    def __iter__(self):
-        return iter(set(self._keys).intersection(self._space))
-
-    def __len__(self):
-        return len(tuple(iter(self)))