Re: Improve join_search_one_level readibilty (one line change)

The whole lnext() stuff all feels a bit old now that Lists are arrays.
I think we'd be better adjusting the code to pass the List index where
we start from rather than the ListCell to start from.  That way we can
use for_each_from() to iterate rather than for_each_cell().  What's
there today feels a bit crufty and there's some element of danger that
the given ListCell does not even belong to the given List.