BUG: conversion of Series to Categorical (pandas-dev#16557)

fix pandas-dev#16524

(cherry picked from commit 9fdea65)

doc/source/whatsnew/v0.20.3.txt

@@ -44,6 +44,7 @@ Conversion
 ^^^^^^^^^^
 
 - Bug in pickle compat prior to the v0.20.x series, when ``UTC`` is a timezone in a Series/DataFrame/Index (:issue:`16608`)
+- Bug in Series construction when passing a Series with ``dtype='category'`` (:issue:`16524`).
 
 Indexing
 ^^^^^^^^

pandas/core/internals.py

@@ -471,7 +471,7 @@ def astype(self, dtype, copy=False, errors='raise', values=None, **kwargs):
                             **kwargs)
 
     def _astype(self, dtype, copy=False, errors='raise', values=None,
-                klass=None, mgr=None, **kwargs):
+                klass=None, mgr=None, raise_on_error=False, **kwargs):
         """
         Coerce to the new type (if copy=True, return a new copy)
         raise on an except if raise == True

pandas/tests/series/test_dtypes.py

@@ -248,3 +248,12 @@ def test_intercept_astype_object(self):
 
         result = df.values.squeeze()
         assert (result[:, 0] == expected.values).all()
+
+    def test_series_to_categorical(self):
+        # see gh-16524: test conversion of Series to Categorical
+        series = Series(['a', 'b', 'c'])
+
+        result = Series(series, dtype='category')
+        expected = Series(['a', 'b', 'c'], dtype='category')
+
+        tm.assert_series_equal(result, expected)