[swift-evolution] Inquiry: Status of SR-122 ?

[plx]

I was preparing a proposal-sketch relating to this earlier discussion: http://article.gmane.org/gmane.comp.lang.swift.evolution/1629

…which is largely about inserting "intermediate steps” between `SequenceType` and `CollectionType`, but to get the full benefit would likely wind up requiring modifications to the API on the `*Index` types (e.g. `ForwardIndexType`, which at present is required of a `CollectionType`’s `Index`).

Searching for prior discussion/work I found this bug: https://bugs.swift.org/browse/SR-122 , and was curious if anything further has happened on that topic?