bpo-43995: Fix reference leak in test_grammar (GH-25764)

Author: Erlend Egeberg Aasland

Lib/test/test_grammar.py

@@ -2,6 +2,7 @@
 # This just tests whether the parser accepts them all.
 
 from test.support import check_syntax_error
+from test.support import import_helper
 from test.support.warnings_helper import check_syntax_warning
 import inspect
 import unittest
@@ -392,13 +393,13 @@ def test_var_annot_module_semantics(self):
  def test_var_annot_in_module(self):
  # check that functions fail the same way when executed
  # outside of module where they were defined
- from test.ann_module3 import f_bad_ann, g_bad_ann, D_bad_ann
+ ann_module3 = import_helper.import_fresh_module("test.ann_module3")
  with self.assertRaises(NameError):
- f_bad_ann()
+ ann_module3.f_bad_ann()
  with self.assertRaises(NameError):
- g_bad_ann()
+ ann_module3.g_bad_ann()
  with self.assertRaises(NameError):
- D_bad_ann(5)
+ ann_module3.D_bad_ann(5)
 
  def test_var_annot_simple_exec(self):
  gns = {}; lns= {}