Randomize revisions

arkindex/documents/migrations/0024_migrate_datasource.py

 # Generated by Django 3.1.3 on 2020-11-30 10:40
 
 import os
+import uuid
 
 from django.db import migrations, models
 
@@ -53,19 +54,22 @@ def migrate_data_sources(apps, schema_editor):
                 'type': str(source.type),
             }
         )
-        revision, _ = repo.revisions.get_or_create(
-            hash='0' * 32,
-            message='Migrated DataSource',
-            author='Arkindex',
-        )
-        # There can be multiple DataSources with the same slug and revision,
-        # but with a different type, so we have to use get_or_create.
-        version, _ = worker.workerversion_set.get_or_create(
+
+        # To ensure we cannot get duplicate worker version IDs when re-applying
+        # unique constraints later, we just keep on trying to get a new revision.
+        created = False
+        while not created:
+            revision, created = repo.revisions.get_or_create(
+                hash=uuid.uuid4().hex,
+                message='Migrated DataSource',
+                author='Arkindex',
+            )
+
+        version = worker.workerversion_set.create(
             revision=revision,
-            defaults={
-                'configuration': {}
-            },
+            configuration={},
         )
+
         source.elements.update(source=None, worker_version=version)
         source.classifications.update(source=None, worker_version=version)
         source.transcriptions.update(source=None, worker_version=version)