Fix caching error found by regrtest -R (#10229)
diff --git a/Lib/test/test_gettext.py b/Lib/test/test_gettext.py
index 69ffcb7..634c607 100644
--- a/Lib/test/test_gettext.py
+++ b/Lib/test/test_gettext.py
@@ -75,6 +75,7 @@
         fp.close()
         self.env = support.EnvironmentVarGuard()
         self.env['LANGUAGE'] = 'xx'
+        gettext._translations.clear()
 
     def tearDown(self):
         self.env.__exit__()