Migrate attachments s3 to new pattern

So remove the compatibility code altogether

attachment_s3/migrations/9.0.1.1.0/pre-migration.py

@@ -0,0 +1,20 @@
+# -*- coding: utf-8 -*-
+# Copyright 2016 Camptocamp SA
+# License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl.html)
+
+import os
+
+
+def migrate(cr, version):
+    cr.execute("""
+        SELECT value FROM ir_config_parameter
+        WHERE key = 'ir_attachment.location'
+    """)
+    row = cr.fetchone()
+    bucket = os.environ.get('AWS_BUCKETNAME')
+    if row[0] == 's3' and bucket:
+        cr.execute("""
+            UPDATE ir_attachment
+            SET store_fname = 's3://' || %s || '/' || store_fname
+            WHERE store_fname IS NOT NULL AND store_fname NOT LIKE '%%/%%'
+        """, (os.environ['AWS_BUCKETNAME'],))