Impacted versions:
9.0 Community & 9.0 Enterprise

Steps to reproduce:
- Open up a V9 runbot
- Go to projects and click on the issues item, for example for the project 'Research & Development':
  ![image](https://cloud.githubusercontent.com/assets/6352350/13873686/65f2c31c-ecf3-11e5-917a-38df2832bd00.png)
- The project tasks view is opened in place of the project issues. (notice that this only happens every once in a while, about once in five attempts) Example:
  ![image](https://cloud.githubusercontent.com/assets/6352350/13873789/14798b64-ecf4-11e5-9b77-f2ad5d3a8adc.png)

Current behavior:
Every once in a while (about one out of five attempts) after clicking on the issues button it will open up the project tasks, not the issues.

Expected behavior:
When you click on the issues the view with all issues opens, not the view for all tasks.

addons/project_issue/project_issue.py
res = super(project_issue, self)._notification_get_recipient_groups(cr, uid, ids, message, recipients, context=context)
        new_action_id = self.pool['ir.model.data'].xmlid_to_res_id(cr, uid, 'project_issue.project_issue_categ_act0')
        take_action = self._notification_link_helper(cr, uid, ids, 'assign', context=context)
        new_action = self._notification_link_helper(cr, uid, ids, 'new', context=context, action_id=new_action_id)
        task_record = self.browse(cr, uid, ids[0], context=context)
        actions = []
        if not task_record.user_id:
            actions.append({'url': take_action, 'title': _('I take it')})
        else:
            actions.append({'url': new_action, 'title': _('New Issue')})
        res['group_project_user'] = {
            'actions': actions
        }
        return res
    @api.cr_uid_context
    def message_get_reply_to(self, cr, uid, ids, default=None, context=None):