Identify and fix any future reduction w/ noncopyable types issues.

[camio]

PR #378 fixed several issues related to noncopyable types and their usage with future reductions (e.g. future<future<R>> collapsing to future<R>. This code has been reworked substantially since the PR was made and @sean-parent thinks this may have been fixed. This task is to confirm that it was fixed and, if not, fixing it.

Acceptance Criteria

• Identify whether or not noncopyable types work properly with future reductions.
• If noncopyable types do not work properly, fix them.