Merge branch 'master' into enh_14355

doc/source/whatsnew/v0.21.0.txt

@@ -186,6 +186,7 @@ Other Enhancements
 - :func:`date_range` now accepts 'Y' in addition to 'A' as an alias for end of year (:issue:`9313`)
 - Integration with `Apache Parquet <https://parquet.apache.org/>`__, including a new top-level :func:`read_parquet` and :func:`DataFrame.to_parquet` method, see :ref:`here <io.parquet>`. (:issue:`15838`, :issue:`17438`)
 - :func:`DataFrame.add_prefix` and :func:`DataFrame.add_suffix` now accept strings containing the '%' character. (:issue:`17151`)
+- Read/write methods that infer compression (:func:`read_csv`, :func:`read_table`, :func:`read_pickle`, and :meth:`~DataFrame.to_pickle`) can now infer from non-string paths, such as ``pathlib.Path`` objects (:issue:`17206`).
 - :func:`DataFrame.merge` now accepts index level names as `on`, `left_on`, and `right_on` parameters, allowing frames to be merged on a combination of columns and index levels (:issue:`14355`)
 - `read_*` methods can now infer compression from non-string paths, such as ``pathlib.Path`` objects (:issue:`17206`).
 - :func:`pd.read_sas()` now recognizes much more of the most frequently used date (datetime) formats in SAS7BDAT files (:issue:`15871`).

pandas/core/groupby.py

@@ -2776,7 +2776,8 @@ def is_in_obj(gpr):
 
         elif is_in_axis(gpr):  # df.groupby('name')
             if gpr in obj:
-                obj._check_column_or_level_ambiguity(gpr)
+                if validate:
+                    obj._check_column_or_level_ambiguity(gpr)
                 in_axis, name, gpr = True, gpr, obj[gpr]
                 exclusions.append(name)
             elif obj._is_index_reference(gpr):