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.

groups='base.group_user'),
        'working_hours_close': fields.function(_compute_day, string='Working Hours to close the Issue',
                                               multi='compute_day', type="float",
                                               store={'project.issue': (lambda self, cr, uid, ids, c={}: ids, ['date_closed'], 10)},
                                               groups='base.group_user'),
        'inactivity_days': fields.function(_compute_day, string='Days since last action',
                                           multi='compute_day', type="integer", help="Difference in days between last action and current date",
                                           groups='base.group_user'),
        'color': fields.integer('Color Index'),
        'user_email': fields.related('user_id', 'email', type='char', string='User Email', readonly=True),
        'date_action_last': fields.datetime('Last Action', readonly=1),
        'date_action_next': fields.datetime('Next Action', readonly=1),
        'legend_blocked': fields.related("stage_id", "legend_blocked", type="char", string='Kanban Blocked Explanation'),
        'legend_done': fields.related("stage_id", "legend_done", type="char", string='Kanban Valid Explanation'),
        'legend_normal': fields.related("stage_id", "legend_normal", type="char", string='Kanban Ongoing Explanation'),
    }
    _defaults = {
        'active': 1,
        'team_id': lambda s, cr, uid, c: s.pool['crm.team']._get_default_team_id(cr, uid, context=c),
        'stage_id': lambda s, cr, uid, c: s._get_default_stage_id(cr, uid, c),
        'company_id': lambda s, cr, uid, c: s.pool['res.users']._get_company(cr, uid, context=c),
        'priority': '0',
        'kanban_state': 'normal',
        'date_last_stage_update': fields.datetime.now,
        'user_id': lambda obj, cr, uid, context: uid,
    }
    _group_by_full = {
        'stage_id': _read_group_stage_ids
    }
    def copy(self, cr, uid, id, default=None, context=None):