Fix SF bug [ #450245 ] Error in parsing future stmts

Add test case to cover multiple future statements on separate lines of
a module.
diff --git a/Lib/test/test_future.py b/Lib/test/test_future.py
index ba0763b..764584c 100644
--- a/Lib/test/test_future.py
+++ b/Lib/test/test_future.py
@@ -17,6 +17,9 @@
 unload('test_future2')
 import test_future2
 
+unload('test_future3')
+import test_future3
+
 # The remaining tests should fail
 try:
     import badsyntax_future3