'Throw exception if merge. DocTypes cannot be merged.'

def before_rename(self, old, new, merge=False):

    if ((not self.custom) and (frappe.session.user != u'Administrator')):
        frappe.throw(_(u'DocType    can    only    be    renamed    by    Administrator'))
    self.check_developer_mode()
    self.validate_name(new)
    if merge:
        frappe.throw(_(u'DocType    can    not    be    merged'))
