Omit unit tests directory from all coverage runs

tox.ini

@@ -21,13 +21,17 @@ setenv =
 commands =
   stestr run --no-subunit-trace {posargs}
   coverage combine
-  coverage report --fail-under=75 --skip-covered --omit={toxinidir}/coriolis/tests/*
+  coverage report --fail-under=75 --skip-covered
   coverage html -d cover
   coverage xml -o cover/coverage.xml
 
 [testenv:venv]
 commands = {posargs}
 
+[coverage:run]
+source = coriolis
+omit = coriolis/tests/*
+
 [flake8]
 # E125 is deliberately excluded. See https://github.com/jcrocholl/pep8/issues/126
 # E251 Skipped due to https://github.com/jcrocholl/pep8/issues/301