109.13.00

- Fixed `Pipe.iter`'s handling of a closed pipe.

  Fixed the handling by `Pipe.iter` and related foldy functions that
  handle one element at a time, which behaved surprisingly with a pipe
  whose read end has been closed.  These functions had worked by
  reading a queue as a batch and then applying the user function to
  each queue element.  But if the pipe's read end is closed during the
  processing of one queue element, no subsequent element should be
  processed.  Prior to this fix, the `iter` didn't notice the pipe was
  closed for read until it went to read the next batch.
- Renamed `Pipe.read_one` as `Pipe.read_one`', and added
  `Pipe.read_one` that reads a single element.