_action_download_attachments missing

[fdvarela]

ValueError: "'ir.attachment' object has no attribute '_action_download_attachments'" while evaluating
u"if object:\n action = self.browse(cr,uid,context.get('active_ids',\n []))._action_download_attachments()"

Upon installation in a v8 system, select some attachments and click on More -> Download Attachments
Error appears immediately.

Checking the code seems that function referenced in the Server Action does not exist in the code.
_action_download_attachments