Issue #7449, part 10: test_cmd imports trace module using test_support.import_module()
Issue #7449, part 10: test_cmd imports trace module using test_support.import_module()

Use test_support.import_module() instead of import to raise a SkipTest
exception if the import fail. Import trace fails if the threading module is
missing.

See also part 3: test_doctest: import trace module in test_coverage().

sk-/python2.7-type-annotator,sk-/python2.7-type-annotator,sk-/python2.7-type-annotator