[perl #129787] die/CATCH inside a start-block with a channel heisenbugs

[via RT]

# New Ticket Created by  Wenzel Peppmeyer 
# Please include the string:  [perl #129787]
# in the subject line of all future correspondence about this issue. 
# <URL: https://rt.perl.org/Ticket/Display.html?id=129787 >


sub f(){
     my $c = Channel.new;

     start {
         for 1..* {
             CATCH { default { note .Str } }

             $c.send($_);
             die 'bad';
         }
     }

     $c.list
}

.say for f;

# sometimes it works
# sometimes it counts to 20 and outputs: 
#     Command terminated
# sometimes it outputs some numbers and 'bad's end then some 
# unicode-garbage
# sometimes it outputs a few 100s 'bad' and then stalls with one thread at 
# 100% CPU
# heisenbug rate is about 1/3
#
# also it seams to eat up plenty of RAM while it's running without the 
# die/CATCH