Fix signal handling in child threads.

Author: ioquatix

lib/async/container/threaded.rb

@@ -90,7 +90,10 @@ def exec(*arguments, ready: true, **options)
 				def self.fork(**options)
 					self.new(**options) do |thread|
 						::Thread.new do
-							yield Instance.for(thread)
+							# This could be a configuration option (see forked implementation too):
+							::Thread.handle_interrupt(SignalException => :immediate) do
+								yield Instance.for(thread)
+							end
 						end
 					end
 				end