scala/scala — pull request #1143 by axel22 (2012-08-15 14:43:46+00:00)
Title: Fixes SI-6150.

Removes the `VectorReusableCBF` and pattern matching on it in optimized `Vector` methods.
Instead, we now have a new `ReusableCBF` instance in `IndexedSeq` and check for equality
when trying to optimize `:+`, `+:` and `updated`.
This overridden `ReusableCBF` is used by `IndexedSeq`, `immutable.IndexedSeq` and
`immutable.Vector`.

The net effect is that calling `:+` and similar methods on a `Vector` instance with
a `CBF` that came from `IndexedSeq` or somewhere lower in the hierarchy will always
create a `Vector` using the optimized method.

Review by @jsuereth.