Removed unnecessary filter argument in AggBase.__getitem__ (#1903)

* Remove excessive filter kwarg appearing in AggBase direct aggregation access (#1902)

* Typo (#1902)

(cherry picked from commit b06a222)

Author: rikkt0r

Diff for: elasticsearch_dsl/aggs.py

@@ -127,7 +127,7 @@ def __getitem__(self, agg_name: str) -> Agg[_R]:
         # make sure we're not mutating a shared state - whenever accessing a
         # bucket, return a shallow copy of it to be safe
         if isinstance(agg, Bucket):
-            agg = A(agg.name, filter=None, **agg._params)
+            agg = A(agg.name, **agg._params)
             # be sure to store the copy so any modifications to it will affect us
             self._params["aggs"][agg_name] = agg
 

Diff for: tests/test_aggs.py

@@ -476,3 +476,12 @@ def test_top_metrics_aggregation() -> None:
     assert {
         "top_metrics": {"metrics": {"field": "m"}, "sort": {"s": "desc"}}
     } == a.to_dict()
+
+
+def test_bucket_agg_with_filter() -> None:
+    b = aggs.Filter(query.Terms(something=[1, 2, 3]))
+
+    a = aggs.Terms(field="some_field", size=100)
+    a.bucket("b", b)
+
+    assert a.aggs["b"] == a["b"]  # a['b'] threw exception before patch #1902