Code review comment for lp:~frankban/launchpad/bug-993510

Thanks Benji, added a test as you suggested.

$ bin/test -cvvt lp.testing.tests.test_testcase.TestRemoveLoggingHandlers
Running tests at level 1
Running zope.testing.testrunner.layer.UnitTests tests:
  Set up zope.testing.testrunner.layer.UnitTests in 0.000 seconds.
  Running:
 lp.testing.tests.test_testcase.TestRemoveLoggingHandlers.test_handlers_list_is_empty
  Ran 1 tests with 0 failures and 0 errors in 0.001 seconds.
Tearing down left over layers:
  Tear down zope.testing.testrunner.layer.UnitTests in 0.000 seconds.