Stop trying to write into the stdlib during lib2to3 tests (#12331).
This prevents tests from failing when run from a Python installed in a
read-only directory.
diff --git a/Misc/NEWS b/Misc/NEWS
index aab5e1a..e1060f6 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -140,6 +140,9 @@
Tests
-----
+- Issue #12331: The test suite for lib2to3 can now run from an installed
+ Python.
+
- Issue #12626: In regrtest, allow to filter tests using a glob filter
with the ``-m`` (or ``--match``) option. This works with all test cases
using the unittest module. This is useful with long test suites