Database access in data migrations defaults to the 'default' database. Force it to the user selected database instead.

Signed-off-by: Roberto Rosario <roberto.rosario.gonzalez@gmail.com>

mayan/apps/documents/migrations/0031_convert_uuid.py

@@ -9,7 +9,7 @@ from django.db import migrations
 def convert_uuid_to_hex(apps, schema_editor):
     Document = apps.get_model('documents', 'Document')
 
-    for document in Document.objects.all():
+    for document in Document.objects.using(schema_editor.connection.alias).all():
         document.uuid = uuid.UUID(document.uuid).hex
         document.save()