Package resolution infelicity

gistfile1.pl

Given:

lib/Pack.pm:


               class Pack {
               
                  use Pack::Util::Collection;
                  our $collection;
               
                  method debug(Str $f) {
                     say "foo";
                  }
               
                  method collection {
                     $collection //= Pack::Util::Collection.new;
                  }
                  method bar() {
                     self.collection.bar();
                  }
               }

And lib/Pack/Util/Collection.pm:

               
class Pack::Util::Collection {
                  method bar {
                     say Pack.WHO;
                     Pack.debug("foo");
                  }
               }

Then 

perl6 -Ilib -e 'use Pack; my $p = Pack.new; $p.bar'
Util => (Util)
Method 'debug' not found for invocant of class 'Pack'
  in method bar at /home/jonathan/devel/perl6/packtest/lib/Pack/Util/Collection.pm:4
  in method bar at /home/jonathan/devel/perl6/packtest/lib/Pack.pm:14
  in block <unit> at -e:1
  in any <unit-outer> at -e:1