Evergreen added support for direct links to plain-text logs. With logkeeper, this is accomplished by adding the GET parameter raw=1 to the URL for the logkeeper logs. The following change should be made to TestReport.as_dict() in buildscripts/resmokelib/testing/report.py to opt-in to this capability:

if test_info.url_endpoint is not None:
    result["url"] = test_info.url_endpoint
    result["url_raw"] = test_info.url_endpoint + "?raw=1"