This happens only while running the tests sequentially and also with whole test suite. This error is present in optional GCC build consistently as below : 

https://travis-ci.org/python/cpython/jobs/531845094#L2103

Running whole test suite sequentially in verbose mode brings below message locally : 

test_get_type_hints_modules_forwardref (test.test_typing.GetTypeHintTests) ... unexpected success

I am not sure of the relation in running this sequentially along with the whole test suite. Feel free to close this if this is a false positive.