Select in some cases hangs forever

[kostya]

this works as expected:

ch1 = Channel(Int32).new
ch2 = Channel(Bool).new

spawn do
  select
  when val = ch1.receive
    p val
    exit
  when ch2.receive
    p :not_happen
  end
end

spawn do
  select
  when ch1.send(1)
    p :sended
  when ch2.receive
    p :not_happen
  end
end

sleep

output 1 and exit.

but if i change order of receive and send, it hangs forever, but expected to work.

ch1 = Channel(Int32).new
ch2 = Channel(Bool).new

spawn do
  select
  when ch1.send(1)
    p :sended
  when ch2.receive
    p :not_happen
  end
end

spawn do
  select
  when val = ch1.receive
    p val
    exit
  when ch2.receive
    p :not_happen
  end
end

sleep