assignment using portlets.xml fails

[iham]

this is a chicken/egg problem:

assigning a portlet with no content doesn't work, as the "content" (which is a uid of a content-object) is required. but as there is no content (at least none of which i'd know the uid of. as it is not possible to know the uid of an object beforehand (or even create a manual uid) i can't know that number... you see, where this is going.

letting the assignment initialise without content would fix that:
assign portlet (generic setup) - create content (like in a post_handler) - get the uid and add it to that portlet: done.

[iham]

... having a required=True on the choice is also a problem with that