FIX: Prefix field still too limited for legacy data

Fingers crossed this works I don't have the actual data locally... I know I'm making a mess but needs must.

I genuinely hate whoever decided prefixes were a good idea now.

assets/migrations/0008_auto_20191205_1937_squashed_0009_auto_20191205_2041.py

@@ -42,7 +42,7 @@ class Migration(migrations.Migration):
         migrations.AddField(
             model_name='asset',
             name='asset_id_prefix',
-            field=models.CharField(default='', max_length=5),
+            field=models.CharField(default='', max_length=8),
         ),
         migrations.RunPython(
             code=forwards,
@@ -56,10 +56,5 @@ class Migration(migrations.Migration):
             model_name='asset',
             name='asset_id',
             field=models.CharField(max_length=15, unique=True),
-        ),
-        migrations.AlterField(
-            model_name='asset',
-            name='asset_id_prefix',
-            field=models.CharField(default='', max_length=8),
-        ),
+        )
     ]