Closes #15620: check for presence of readline.clear_history(), which is apparently missing on some readline versions, before calling it in the test.
diff --git a/Lib/test/test_readline.py b/Lib/test/test_readline.py
index 5483dd3..fe74939 100644
--- a/Lib/test/test_readline.py
+++ b/Lib/test/test_readline.py
@@ -17,7 +17,9 @@
                      "The history update test cannot be run because the "
                      "clear_history method is not available.")
     def testHistoryUpdates(self):
-        readline.clear_history()
+        # Some GNU versions of readline do not support clear_history
+        if hasattr('readline', 'clear_history'):
+            readline.clear_history()
 
         readline.add_history("first line")
         readline.add_history("second line")