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
def _issue_count(self, cr, uid, ids, field_name, arg, context=None):
        Issue = self.pool['project.issue']
        return {
            partner_id: Issue.search_count(cr,uid, [('partner_id', '=', partner_id)])
            for partner_id in ids
        }
    """ Inherits partner and adds Issue information in the partner form """
    _inherit = 'res.partner'
    _columns = {
        'issue_count': fields.function(_issue_count, string='# Issues', type='integer'),
    }