
This commit fixes running subunit-trace on older versions of python, by inlining the total_seconds method from newer versions of python. While tempest-lib is nominally only for python > 2.7 (which is all we test) subunit-trace is slightly different. Since it is expected to be used in the unit test workflows of projects, some of which still run on older python. Change-Id: I33c337bfb376a27bf02cc2d16a69dafba2cea41f