[3.9] bpo-41970: Avoid test failure in test_lib2to3 if the module is already imported (pythonGH-22595)

…

Automerge-Triggered-By: @pablogsal.
(cherry picked from commit 4a9f82f)

Co-authored-by: Pablo Galindo <[email protected]>

Author: pablogsal

Lib/test/test_lib2to3.py

@@ -1,8 +1,8 @@
 import unittest
-from test.support import check_warnings
+from test.support import check_warnings, import_fresh_module
 
 with check_warnings(("", PendingDeprecationWarning)):
-    from lib2to3.tests import load_tests
+    load_tests = import_fresh_module('lib2to3.tests', fresh=['lib2to3']).load_tests
 
 if __name__ == '__main__':
     unittest.main()

Misc/NEWS.d/next/Tests/2020-10-08-14-00-17.bpo-41970.aZ8QFf.rst

@@ -0,0 +1,2 @@
+Avoid a test failure in ``test_lib2to3`` if the module has already imported
+at the time the test executes. Patch by Pablo Galindo.