[perl #128991] [CONC] Apparent race condition with `done` and ultra-short Supply.interval

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# New Ticket Created by  Zoffix Znet 
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This code produces the following exception with Rakudo dd5c28. If interval is 
changed to a larger
value, the issue does not occur:

react {
    whenever Supply.interval(.001) {
        done if $++ > 1000;
    }
}
sleep 1;

Unhandled exception in code scheduled on thread 4
Access denied to keep/break this Promise; already vowed
  in any  at 
/home/zoffix/.rakudobrew/moar-nom/install/share/perl6/runtime/CORE.setting.moarvm
 line 1
  in sub THROW-NIL at 
/home/zoffix/.rakudobrew/moar-nom/install/share/perl6/runtime/CORE.setting.moarvm
 line 1
  in block  at test.p6 line 4