test_model: Fix compatibility with pytest-xdist
Using .now() produces data that differs between xdist processes, as files are imported after forking, and xdist requires consistent data across processes.
Migrated from D6841 (view on Phabricator)
Using .now() produces data that differs between xdist processes, as files are imported after forking, and xdist requires consistent data across processes.
Migrated from D6841 (view on Phabricator)