bpo-38328: Speed up the creation time of constant list and set display. (GH-17114)

diff --git a/Lib/test/test_sys.py b/Lib/test/test_sys.py
index 9961dee..947c935 100644
--- a/Lib/test/test_sys.py
+++ b/Lib/test/test_sys.py
@@ -1222,7 +1222,7 @@
         # list
         samples = [[], [1,2,3], ['1', '2', '3']]
         for sample in samples:
-            check(sample, vsize('Pn') + len(sample)*self.P)
+            check(list(sample), vsize('Pn') + len(sample)*self.P)
         # sortwrapper (list)
         # XXX
         # cmpwrapper (list)