Fix RemoteChannel iterator interface (#100)

Author: danielwe

src/Distributed.jl

@@ -15,7 +15,7 @@ using Base: Process, Semaphore, JLOptions, buffer_writes, @async_unwrap,
             julia_cmd, AsyncGenerator, acquire, release, invokelatest,
             shell_escape_posixly, shell_escape_csh,
             shell_escape_wincmd, escape_microsoft_c_args,
-            uv_error, something, notnothing, isbuffered, mapany
+            uv_error, something, notnothing, isbuffered, mapany, SizeUnknown
 using Base.Threads: Event
 
 using Serialization, Sockets

test/distributed_exec.jl

@@ -473,6 +473,8 @@ test_iteration(RemoteChannel(() -> Channel(10)), RemoteChannel(() -> Channel(10)
     return count
 end
 
+@everywhere test_iteration_collect(ch) = length(collect(ch))
+
 @everywhere function test_iteration_put(ch, total)
     for i in 1:total
         put!(ch, i)
@@ -483,10 +485,16 @@ end
 let ch = RemoteChannel(() -> Channel(1))
     @async test_iteration_put(ch, 10)
     @test 10 == @fetchfrom id_other test_iteration_take(ch)
+    ch = RemoteChannel(() -> Channel(1))
+    @async test_iteration_put(ch, 10)
+    @test 10 == @fetchfrom id_other test_iteration_collect(ch)
     # now reverse
     ch = RemoteChannel(() -> Channel(1))
     @spawnat id_other test_iteration_put(ch, 10)
     @test 10 == test_iteration_take(ch)
+    ch = RemoteChannel(() -> Channel(1))
+    @spawnat id_other test_iteration_put(ch, 10)
+    @test 10 == test_iteration_collect(ch)
 end
 
 # make sure exceptions propagate when waiting on Tasks