'Move mail.message from the given opportunities to the current one. `self` is the
crm.lead record destination for message of `opportunities`.
:param opportunities : recordset of crm.lead to move the messages'

@api.multi
def _merge_opportunity_history(self, opportunities):

    self.ensure_one()
    for opportunity in opportunities:
        for message in opportunity.message_ids:
            message.write({'res_id': self.id, 'subject': (_('From    %s    :    %s') % (opportunity.name, message.subject))})
    return True
