concurrent-ruby-edge Channel.select consumes full(single core) cpu

* `concurrent-ruby` version:       1.1.7
* `concurrent-ruby-edge` used:     yes 

I am running this simple code and I see that select is not blocking on the channels and instead always looping which consumes full(single core) CPU.

require 'concurrent-edge'

Channel = Concurrent::Channel
string1 = Channel.new
string2 = Channel.new

loop do
  Channel.select do |s|
    s.take(string1) {
      puts "string1"
    }
    s.take(string2) { 
      puts "string2"
    }
  end
end

Start by running the supplied concurrent-ruby-edge reproduction and then trace the Channel.select entry point and its channel-waiting behavior. Done means select blocks when both channels are empty and the loop no longer consumes a full CPU core, while still handling values sent to either channel.