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_bytes.py b/Lib/test/test_bytes.py
index 234b56c..d32a44b 100644
--- a/Lib/test/test_bytes.py
+++ b/Lib/test/test_bytes.py
@@ -475,6 +475,27 @@
         self.assertRaises(TypeError, self.type2test(b'abc').lstrip, 'b')
         self.assertRaises(TypeError, self.type2test(b'abc').rstrip, 'b')
 
+    def test_center(self):
+        # Fill character can be either bytes or bytearray (issue 12380)
+        b = self.type2test(b'abc')
+        for fill_type in (bytes, bytearray):
+            self.assertEqual(b.center(7, fill_type(b'-')),
+                             self.type2test(b'--abc--'))
+
+    def test_ljust(self):
+        # Fill character can be either bytes or bytearray (issue 12380)
+        b = self.type2test(b'abc')
+        for fill_type in (bytes, bytearray):
+            self.assertEqual(b.ljust(7, fill_type(b'-')),
+                             self.type2test(b'abc----'))
+
+    def test_rjust(self):
+        # Fill character can be either bytes or bytearray (issue 12380)
+        b = self.type2test(b'abc')
+        for fill_type in (bytes, bytearray):
+            self.assertEqual(b.rjust(7, fill_type(b'-')),
+                             self.type2test(b'----abc'))
+
     def test_ord(self):
         b = self.type2test(b'\0A\x7f\x80\xff')
         self.assertEqual([ord(b[i:i+1]) for i in range(len(b))],