Resolve "Updating own past feedback sets other tutors assignment to is_done=True"

Closes #155 (closed)

.gitlab-ci.yml

@@ -70,7 +70,7 @@ test_pytest:
   services:
     - postgres:9.6
   script:
-    - pytest --cov --ds=grady.settings.test core/tests
+    - pytest -n 4 --cov --ds=grady.settings.test core/tests
   artifacts:
     paths:
       - .coverage
@@ -105,7 +105,7 @@ test_frontend:
     - cp frontend/dist/index.html core/templates
     - python util/format_index.py
     - python manage.py collectstatic --no-input
-    - HEADLESS_TESTS=True pytest --ds=grady.settings.test functional_tests
+    - HEADLESS_TESTS=True pytest -n 4 --ds=grady.settings.test functional_tests
   artifacts:
     paths:
       - .screenshots