cubicweb-searchui #7906496 selected relation may have Null objects in the rset [open]

eg.

2015-10-26 14:28:19 - (cubicweb.web) ERROR: AssertionError()
Traceback (most recent call last):
 File "/home/david/hg/grshells/grshell-cubicweb/cubicweb/web/application.py", line 367, in core_handle
   result = controller.publish(rset=rset)
 File "/home/david/hg/grshells/grshell-cubicweb/cubicweb/web/views/basecontrollers.py", line 133, in publish
   rset=rset, view=view)
 File "/home/david/hg/grshells/grshell-cubicweb/cubicweb/cwvreg.py", line 223, in main_template
   res = obj.render(**kwargs)
 File "/home/david/hg/grshells/grshell-cubicweb/cubicweb/view.py", line 136, in render
   view_func(**context)
 File "/home/david/hg/grshells/grshell-cubicweb/cubes/squareui/views/basetemplates.py", line 38, in call
   self.template_header(self.content_type, view)
 File "/home/david/hg/grshells/grshell-cubicweb/cubes/squareui/views/basetemplates.py", line 43, in template_header
   page_title = page_title or view.page_title()
 File "/home/david/hg/grshells/grshell-cubicweb/cubicweb/view.py", line 275, in page_title
   entity = rset.complete_entity(0, 0)
 File "/home/david/hg/grshells/grshell-cubicweb/cubicweb/rset.py", line 413, in complete_entity
   entity = self.get_entity(row, col)
 File "/home/david/hg/grshells/grshell-cubicweb/logilab/common/logilab/common/decorators.py", line 67, in wrapped
   return self.__call__(*args, **kwargs)
 File "/home/david/hg/grshells/grshell-cubicweb/logilab/common/logilab/common/decorators.py", line 94, in __call__
   _cache[args] = __me.callable(self, *args)
 File "/home/david/hg/grshells/grshell-cubicweb/cubicweb/rset.py", line 441, in get_entity
   return self._build_entity(row, col)
 File "/home/david/hg/grshells/grshell-cubicweb/cubicweb/rset.py", line 480, in _build_entity
   assert eid is not None
AssertionError
prioritynormal
typebug
done in<not specified>
closed by<not specified>