open('less'... example in manual broken

[BobPortmann]

The example given in the manual to write to an external command is broken on master:

> ~/src/julia/julia
               _
   _       _ _(_)_     |  A fresh approach to technical computing
  (_)     | (_) (_)    |  Documentation: http://docs.julialang.org
   _ _   _| |_  __ _   |  Type "?help" for help.
  | | | | | | |/ _` |  |
  | | |_| | | | (_| |  |  Version 0.4.0-dev+7036 (2015-08-27 14:47 UTC)
 _/ |\__'_|_|_|\__'_|  |  Commit 006537f* (0 days old master)
|__/                   |  x86_64-apple-darwin13.4.0

julia> versioninfo()
Julia Version 0.4.0-dev+7036
Commit 006537f* (2015-08-27 14:47 UTC)
Platform Info:
  System: Darwin (x86_64-apple-darwin13.4.0)
  CPU: Intel(R) Core(TM)2 Duo CPU     T9550  @ 2.66GHz
  WORD_SIZE: 64
  BLAS: libopenblas (USE64BITINT DYNAMIC_ARCH NO_AFFINITY Penryn)
  LAPACK: libopenblas
  LIBM: libopenlibm
  LLVM: libLLVM-3.3

julia> open(`less`, "w", STDOUT) do io
           for i = 1:3
               println(io, i)
           end
       end
ERROR: ArgumentError: stream is closed or unusable
 in check_open at stream.jl:322
 in uv_write at stream.jl:924
 in buffer_or_write at stream.jl:952
 in write at stream.jl:992
 in print at strings/io.jl:5
 in print at strings/io.jl:6
 in println at strings/io.jl:8
 in println at stream.jl:238
 in println at stream.jl:554
 in anonymous at none:3
 in open at process.jl:487

julia> 

It seems to have been broken by

80be43723b485edee7539ec6e9a8111384335f31 
Author: Jameson Nash <[email protected]>
Date:   Thu Aug 20 23:54:05 2015 -0400

redesign Process to be a subtype of IO and dispatch read/write to the appropriate stdin/stdout stream

[stevengj]

cc @vtjnash on 80be437