Fix crash of test_*_arbitrary when given objects with the same id
Replaces !805 (closed), using Hypothesis' unique_by
instead of manually trimming lists
Migrated from D8197 (view on Phabricator)
Replaces !805 (closed), using Hypothesis' unique_by
instead of manually trimming lists
Migrated from D8197 (view on Phabricator)