[perl #132170] fork + react + IO::Socket::Async issue

[via RT]

# New Ticket Created by  Brian Duggan 
# Please include the string:  [perl #132170]
# in the subject line of all future correspondence about this issue. 
# <URL: https://rt.perl.org/Ticket/Display.html?id=132170 >


When I export a function that does a fork() and then
a react + whenever + IO::Socket::Async.listen in the
child process, the process only seems to be listening
on the socket the second time I run the code, i.e. only
after .precomp has been written.

To reproduce: 

    1. name the three files below 'try.sh',
      'runme.p6' and 'Server.pm6'.

    2. Run try.sh

I see this output on linux:

    attempt 1
    nc: connect to localhost port 3333 (tcp) failed: Connection refused
    attempt 2
    Connection to localhost 3333 port [tcp/*] succeeded!

And a similiar output on OS/X.  Increasing the time of the sleep
doesn't help.

try.sh:

    #!/bin/sh
    rm -rf .precomp
    for i in 1 2; do
        echo "attempt $i"
        perl6 runme.p6 &
        sleep 5
        echo 'Connecting'
        nc -v localhost 3333
        echo 'Killing'
        killall moar
    done

runme.p6:

    use lib '.';
    use Server;
    start-fork;

Server.pm6:

    use NativeCall;
    sub fork returns int32 is native { * };
    sub start-fork is export {
        unless fork() {
            react whenever IO::Socket::Async.listen('localhost',3333) {
                exit;
            }
        }
    }

Output of perl6 -v:

This is Rakudo version 2017.08 built on MoarVM version 2017.08.1
implementing Perl 6.c.