Ahhh here, a test case seems to be missing. This one here only tries to land on a section that's permitted on another subsite. We'd need another one trying to access a section that's not accessible on *any* subsite with an account that can access *something*.

```
$this->getAndFollowAll("admin/inaccessible-existing-section/?SubsiteID=0");
$this->assertEquals(Subsite::currentSubsiteID(), $subsite1->ID, 'Is redirected to first permitted subsite.');
$this->assertNotRegExp('#^Security/login.*#', $this->mainSession->lastUrl(), 'Is not denied access');
```