@lrowe 1d9d1d775db487c2 : Never test a container for its truth value, use ```if portal is not None```.
Fix: portal.get() should also return the portal from sub-sites

As reported by @lrowe in 725dbfc33d5a76112118a:
It's not guaranteed that getSite will return the portal, it returns the closes component site manager. KSS uses this mechanism to do some magic stuff, and it could be useful to support nested local component sites to customise subsites.

To get the actual portal, one should walk backwards along the acquisition chain (starting with getSite()) until an object directly providing Products.CMFCore.interfaces.ISiteRoot is found.