[perl #125654] Killing a Proc::Async doesn't seem to clean up its file descriptors, causing an abort() from libuv

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# New Ticket Created by  Rob Hoelz 
# Please include the string:  [perl #125654]
# in the subject line of all future correspondence about this issue. 
# <URL: https://rt.perl.org/Ticket/Display.html?id=125654 >


See the attached script.

Removing :w from the call to Proc::Async.new or the tap on $proc.stdout 
prevents this behavior.

When I set a file descriptor limit of 150 via ulimit, Rakudo abort()s after 
about 60 iterations.
use v6;

my @procs;
my @promises;

for ^1000 {
    .say;
    if @procs {
        @procs[*-1].kill;
    }

    my $proc = Proc::Async.new('sleep', '20', :w);
    $proc.stdout.tap(-> $ {});
    @promises.push: $proc.start;
    @procs.push: $proc;
}

await @promises;