fix: resolve IterableList names independently of list attributes

Normal attribute lookup makes string indexing return list methods for item
names such as `count`, and reports absent `append` identifiers as present.
Use `__getattr__` explicitly for identifier lookup and remove its fallback
to list attributes. Ordinary attribute access still exposes list methods.

Add twelve present/absent collision cases with and without prefixes.
The full suite passes 1701 tests, 89 conditional skips, one existing xfail,
and 64 subtests; pinned hooks, type checks, docs and packaging also pass.

Author: FanWu-ai

git/util.py

@@ -1382,7 +1382,7 @@ def __contains__(self, attr: object) -> bool:
 
         # Otherwise make a full name search.
         try:
-            getattr(self, cast(str, attr))  # Use cast to silence mypy.
+            self.__getattr__(cast(str, attr))  # Use cast to silence mypy.
             return True
         except (AttributeError, TypeError):
             return False
@@ -1394,7 +1394,7 @@ def __getattr__(self, attr: str) -> T_IterableObj:
             if getattr(item, self._id_attr) == attr:
                 return item
         # END for each item
-        return list.__getattribute__(self, attr)
+        raise AttributeError(f"No item found with id {attr}")
 
     def __getitem__(  # type: ignore[override]  # pyright: ignore[reportIncompatibleMethodOverride]
         self, index: Union[SupportsIndex, int, slice, str]
@@ -1405,7 +1405,7 @@ def __getitem__(  # type: ignore[override]  # pyright: ignore[reportIncompatible
             raise ValueError("Index should be an int or str")
         else:
             try:
-                return getattr(self, cast(str, index))
+                return self.__getattr__(cast(str, index))
             except AttributeError as e:
                 raise IndexError(f"No item found with id {self._prefix}{index}") from e
         # END handle getattr

test/test_util.py

@@ -862,3 +862,23 @@ def test_mode_str_to_int_accepts_bytes():
     assert mode_str_to_int(b"100644") == 0o100644
     assert mode_str_to_int("644") == 0o644
     assert mode_str_to_int(b"120000") == 0o120000
+
+
+@pytest.mark.parametrize("name", ["sort", "count", "append", "_prefix", "__class__", "ordinary"])
+@pytest.mark.parametrize("prefix", ["", "refs/"])
+def test_iterable_list_name_lookup_ignores_list_attributes(name, prefix):
+    values = IterableList("name", prefix)
+    member = _Member(prefix + name)
+    values.append(member)
+
+    assert values[name] is member
+    assert name in values
+    assert member in values
+    assert values[0] is member
+    assert callable(values.append)
+    assert callable(values.sort)
+
+    del values[name]
+    assert name not in values
+    with pytest.raises(IndexError, match="No item found with id"):
+        values[name]