Issue #12380: PyArg_ParseTuple now accepts a bytearray for the 'c' format.
As a side effect, this now allows the rjust, ljust and center methods of
bytes and bytearray to accept a bytearray argument.

Patch by Petri Lehtinen
diff --git a/Lib/test/test_getargs2.py b/Lib/test/test_getargs2.py
index 3d9c06a..768ea8d 100644
--- a/Lib/test/test_getargs2.py
+++ b/Lib/test/test_getargs2.py
@@ -294,6 +294,15 @@
             self.fail('TypeError should have been raised')
 
 class Bytes_TestCase(unittest.TestCase):
+    def test_c(self):
+        from _testcapi import getargs_c
+        self.assertRaises(TypeError, getargs_c, b'abc')  # len > 1
+        self.assertEqual(getargs_c(b'a'), b'a')
+        self.assertEqual(getargs_c(bytearray(b'a')), b'a')
+        self.assertRaises(TypeError, getargs_c, memoryview(b'a'))
+        self.assertRaises(TypeError, getargs_c, 's')
+        self.assertRaises(TypeError, getargs_c, None)
+
     def test_s(self):
         from _testcapi import getargs_s
         self.assertEqual(getargs_s('abc\xe9'), b'abc\xc3\xa9')