From the output it looks like the tests are indeed running with the xml reporting library but when we attempt to upload the XML result files (src/xunit-results/TEST-*.xml) evergreen complains that no files are found:
[2019/03/12 18:12:46.365] + /opt/python/2.7/bin/python setup.py test --xunit-output=xunit-results [2019/03/12 18:12:46.365] Running tests... [2019/03/12 18:12:46.365] ---------------------------------------------------------------------- [2019/03/12 18:12:46.386] test_uri_options (test_auth.TestAuthURIOptions) ... SKIP (0.021s) ... [2019/03/12 18:51:40.945] Running command 'attach.xunit_results' in "upload test results" (step 3.2 of 5) [2019/03/12 18:51:40.945] Command failed: no test results found