Add test file for scripts in Tools (#13447).

When people find bugs in scripts such as reindent.py, msgfmt.py or
pygettext.py, we have to try to reproduce the bug manually, apply a fix
and test manually again.  The alternative is to only read the code and
trust that it works.  This test file is a way to stop that
unsatisfactory state of things and write proper unit tests instead.
diff --git a/Misc/NEWS b/Misc/NEWS
index 0ab7514..96cfd2d 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -98,6 +98,9 @@
 Library
 -------
 
+- Issue #13447: Add a test file to host regression tests for bugs in the
+  scripts found in the Tools directory.
+
 - Issue #6884: Fix long-standing bugs with MANIFEST.in parsing in distutils
   on Windows.