My recipe worked for me, but I am not surprised that it might fail elsewhere.  Is the specific purpose of the two problemmatic test_trace test to test that trace works with unittest?  It did not seem like it to me.  If not,  test_trace could be decoupled from other tests and use a 'tracetest.py' file that defines one function to be traced.

In the meanwhile, I think you should disable the two tests in test_trace and apply the test_pprint changes, rather than hold test_pprint hostage.