correct BaseGroupBy.__iter__ and def groups [skip ci]

Author: natmokval

pandas/core/groupby/groupby.py

@@ -1012,7 +1012,7 @@ def __iter__(self) -> Iterator[tuple[Hashable, NDFrameT]]:
         # mypy: Argument 1 to "len" has incompatible type "Hashable"; expected "Sized"
         if (
             (is_list_like(level) and len(level) == 1)  # type: ignore[arg-type]
-            or (isinstance(keys, list) and len(keys) == 1)
+            or (isinstance(keys, list))
         ):
             # GH#42795 - when keys is a list, return tuples even when length is 1
             result = (((key,), group) for key, group in result)

pandas/core/groupby/ops.py

@@ -703,7 +703,7 @@ def size(self) -> Series:
     @cache_readonly
     def groups(self) -> dict[Hashable, Index]:
         """dict {group name -> group labels}"""
-        if len(self.groupings) == 1:
+        if len(self.groupings) == 1 and not isinstance(self.shape, tuple):
             return self.groupings[0].groups
         result_index, ids = self.result_index_and_ids
         values = result_index._values