Fix.

Author: serhiy-storchaka

Lib/test/test_capi/test_unicode.py

@@ -1767,13 +1767,6 @@ def test_basic(self):
         self.assertEqual(writer.finish(),
                          "var=long value 'repr'")
 
-    def test_repr_null(self):
-        writer = self.create_writer(0)
-        writer.write_utf8(b'var=', -1)
-        writer.write_repr(NULL)
-        self.assertEqual(writer.finish(),
-                         "var=<NULL>")
-
     def test_write_char(self):
         writer = self.create_writer(0)
         writer.write_char(0)

Modules/_testcapi/unicode.c

@@ -405,7 +405,7 @@ writer_write_ucs4(PyObject *self_raw, PyObject *args)
         size = bsize / sizeof(Py_UCS4);
     }
 
-    int res = PyUnicodeWriter_WriteUCS4(self->writer, (const Py_UCS4 *)s, size);
+    int res = PyUnicodeWriter_WriteUCS4(self->writer, (Py_UCS4 *)s, size);
     if (res < 0) {
         return NULL;
     }