Merge #2565

2565: Fix DB downgrade r=mergify[bot] a=nextgens

Fix DB downgrade. This isn't used in normal operations but is wrong nevertheless.

Co-authored-by: Florent Daigniere <nextgens@freenetproject.org>

core/admin/migrations/versions/f4f0f89e0047_.py

@@ -21,5 +21,5 @@ def upgrade():
 
 def downgrade():
     with op.batch_alter_table('fetch') as batch:
-        batch.drop_column('fetch', 'folders')
+        batch.drop_column('folders')
-        batch.drop_column('fetch', 'scan')
+        batch.drop_column('scan')