Only create trac tables if they do not already exist.

tracdb/testutils.py

@@ -51,6 +51,13 @@ def _create_db_table_for_model(model, schema_editor):
     """
     Use the schema editor API to create the db table for the given (unmanaged) model.
     """
+    with connections["trac"].cursor() as cursor:
+        tables = schema_editor.connection.introspection.table_names(cursor)
+
+    if model._meta.db_table in tables:
+        # Table already created.
+        return
+
     schema_editor.create_model(model)
     if model._meta.model_name in _MODELS_WITH_FAKE_COMPOSITE_PK:
         _replace_primary_key_field_with_autofield(model, schema_editor)