There is no reason for imp.get_magic() to return a mutable bytearray

Python/import.c

@@ -2686,7 +2686,7 @@ imp_get_magic(PyObject *self, PyObject *noargs)
 	buf[2] = (char) ((pyc_magic >> 16) & 0xff);
 	buf[3] = (char) ((pyc_magic >> 24) & 0xff);
 
-	return PyBytes_FromStringAndSize(buf, 4);
+	return PyString_FromStringAndSize(buf, 4);
 }
 
 static PyObject *