rakudo Parametric role breakage when precompiling

rolecompiled.txt

Subject: Curried role compose fails in precompiled modules

When a parametric role is curried it works fine straight from source,
but when the role has been precompiled into a module, a parrot
error is thrown:

cat mod2.pm6
role Foo [ ] { }; role Bar does Foo[] { }
$ PERL6LIB="." perl6 -e 'use mod2; class C does Bar { };'
$ PERL6LIB="." perl6 --target=pir --output=mod2.pir mod2.pm6
$ PERL6LIB="." perl6 -e 'use mod2; class C does Bar { };'
===SORRY!===
flattened parameters must be a hash or array
$ 

http://irclog.perlgeek.de/perl6/2012-10-13#i_6059103

13:49 skids jnthn: any thoughts on https://gist.github.com/3882578 ?  # Apologies of this is a dup line, IRC flapped.
13:49 jnthn skids: looking
13:50       skids: urgh, that looks problematic.
13:50       Please Rakudo-bug it, I'll have a look.
13:52 skids ok, will do.
13:52       jnthn++
13:52 jnthn I'm gonna be doing a bunch of work on pre-comp and so on soonish (automatic pre-comp and so on)