From tokuhirom@gmail.com

When call `run` method in IO​:Socket​::Async.listen routine, perl6-m exits unexpectedly on Mac OS X.

Following test code pass on linux. But it fails on linux.

```
#!/usr/bin/env perl
use strict;
use warnings;
use utf8;
use 5.010000;
use autodie;

use Test​::More;
use IO​::Socket​::INET;

my $pid = fork();
if ($pid > 0) { # parent
  say 'sleep';

  sleep 3;

  say 'connect';
  my $sock = IO​::Socket​::INET->new(PeerAddr => 'localhost​:5000');
  $sock or die;
  my $msg = <$sock>;
  is $msg, "yo\n";
  kill 'TERM', $pid;
  waitpid $pid, 0;
} elsif ($pid == 0) {
  say 'executing server';
  exec 'perl6-m', '-e', <<'EOF';
use v6;

sub MAIN($port=5000) {
  react {
  whenever IO​::Socket​::Async.listen('127.0.0.1', $port) -> $conn {
  run 'ls'; # process exits at here.
  await $conn.print("yo\n");
  $conn.close();
  }
  }
}
EOF
} else {
die 'fork failed';
}

done_testing;
```

output on linux​:
```
sleep
executing server
connect
foo.pl6 hoge.pl projects.json
ok 1
1..1
```

output on mac​:
```
sleep
executing server
connect
LICENSE META6.json README.md bin eg hoge.pl lib server.pl6 t
not ok 1
# Failed test at hoge.pl line 21.
# got​: undef
# expected​: 'yo
# '
1..1
# Looks like you failed 1 test of 1.
```

Version is​:
```
This is perl6 version 2015.09-210-gef814c3 built on MoarVM version 2015.09-39-g1434283
```