Fix IO::Path.new with 0 allomorph
Fix IO::Path.new with 0 allomorph

Bug find: https://irclog.perlgeek.de/perl6/2017-07-16#i_14878891

nbrown/rakudo,awwaiid/rakudo,softmoth/rakudo,labster/rakudo,awwaiid/rakudo,nbrown/rakudo,raydiak/rakudo,nbrown/rakudo,sjn/rakudo,usev6/rakudo,Gnouc/rakudo,Gnouc/rakudo,rakudo/rakudo,softmoth/rakudo,salortiz/rakudo,salortiz/rakudo,tbrowder/rakudo,tbrowder/rakudo,MasterDuke17/rakudo,jonathanstowe/rakudo,tbrowder/rakudo,jonathanstowe/rakudo,tbrowder/rakudo,usev6/rakudo,rakudo/rakudo,lucasbuchala/rakudo,awwaiid/rakudo,softmoth/rakudo,MasterDuke17/rakudo,softmoth/rakudo,sjn/rakudo,raydiak/rakudo,labster/rakudo,Gnouc/rakudo,nbrown/rakudo,jonathanstowe/rakudo,jonathanstowe/rakudo,nbrown/rakudo,jonathanstowe/rakudo,lucasbuchala/rakudo,MasterDuke17/rakudo,usev6/rakudo,lucasbuchala/rakudo,labster/rakudo,sjn/rakudo,raydiak/rakudo,Gnouc/rakudo,awwaiid/rakudo,tony-o/rakudo,rakudo/rakudo,raydiak/rakudo,rakudo/rakudo,usev6/rakudo,MasterDuke17/rakudo,tbrowder/rakudo,tbrowder/rakudo,Gnouc/rakudo,tony-o/rakudo,salortiz/rakudo,rakudo/rakudo,rakudo/rakudo,Gnouc/rakudo,softmoth/rakudo,salortiz/rakudo,labster/rakudo,labster/rakudo,tony-o/rakudo,awwaiid/rakudo,salortiz/rakudo,labster/rakudo,lucasbuchala/rakudo,MasterDuke17/rakudo,tony-o/rakudo,sjn/rakudo,tony-o/rakudo,lucasbuchala/rakudo,nbrown/rakudo,MasterDuke17/rakudo,usev6/rakudo,salortiz/rakudo,sjn/rakudo,tony-o/rakudo