[perl #129247] [BUG] Wait on a Supply after begin tap is hanging

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# New Ticket Created by  Pierre VIGIER 
# Please include the string:  [perl #129247]
# in the subject line of all future correspondence about this issue. 
# <URL: https://rt.perl.org/Ticket/Display.html?id=129247 >


Hi,

i stumbled a across a strange behaviour when playing with Supplier, i tried to 
gulf it down, starting from the documentation of supply. The following code, 
taken from the documentation and slightly modified is working as expected:

my $s = Supplier.new;
my $l = $s.Supply();
start {
  sleep 1;
  $s.emit(1);
  $s.emit(2);
  $s.done;
}
$l.wait;
say "done";

If i tap the $l variable to display the value that are supplied by the 
supplier, it then hangs indefinitely:

my $s = Supplier.new;
my $l = $s.Supply();
$l.tap( -> $v { say "got : $v" } );
start {
  sleep 1;
  $s.emit(1);
  $s.emit(2);
  $s.done;
}
$l.wait;
say "done";

Pierre