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/Python/getargs.c b/Python/getargs.c
index 4b57153..c3da368 100644
--- a/Python/getargs.c
+++ b/Python/getargs.c
@@ -828,6 +828,8 @@
         char *p = va_arg(*p_va, char *);
         if (PyBytes_Check(arg) && PyBytes_Size(arg) == 1)
             *p = PyBytes_AS_STRING(arg)[0];
+        else if (PyByteArray_Check(arg) && PyByteArray_Size(arg) == 1)
+            *p = PyByteArray_AS_STRING(arg)[0];
         else
             return converterr("a byte string of length 1", arg, msgbuf, bufsize);
         break;