Fix installation into an incomplete repository
Fix installation into an incomplete repository

If using a new, plain directory as a CompUnit::Repository::Installation,
we tried to access directories that did not yet exist.

tony-o/rakudo,Gnouc/rakudo,zostay/rakudo,b2gills/rakudo,rakudo/rakudo,tony-o/rakudo,usev6/rakudo,tony-o/rakudo,usev6/rakudo,tony-o/rakudo,samcv/rakudo,MasterDuke17/rakudo,rakudo/rakudo,labster/rakudo,rakudo/rakudo,tbrowder/rakudo,lucasbuchala/rakudo,b2gills/rakudo,b2gills/rakudo,tbrowder/rakudo,salortiz/rakudo,salortiz/rakudo,softmoth/rakudo,MasterDuke17/rakudo,tony-o/rakudo,Gnouc/rakudo,zostay/rakudo,awwaiid/rakudo,rakudo/rakudo,softmoth/rakudo,awwaiid/rakudo,softmoth/rakudo,usev6/rakudo,rakudo/rakudo,Gnouc/rakudo,tbrowder/rakudo,MasterDuke17/rakudo,raydiak/rakudo,raydiak/rakudo,lucasbuchala/rakudo,salortiz/rakudo,nbrown/rakudo,labster/rakudo,softmoth/rakudo,jonathanstowe/rakudo,awwaiid/rakudo,sjn/rakudo,softmoth/rakudo,jonathanstowe/rakudo,usev6/rakudo,jonathanstowe/rakudo,zostay/rakudo,Gnouc/rakudo,labster/rakudo,samcv/rakudo,salortiz/rakudo,MasterDuke17/rakudo,nbrown/rakudo,lucasbuchala/rakudo,MasterDuke17/rakudo,awwaiid/rakudo,nbrown/rakudo,sjn/rakudo,raydiak/rakudo,awwaiid/rakudo,b2gills/rakudo,nbrown/rakudo,sjn/rakudo,Gnouc/rakudo,tbrowder/rakudo,MasterDuke17/rakudo,samcv/rakudo,nbrown/rakudo,labster/rakudo,zostay/rakudo,usev6/rakudo,jonathanstowe/rakudo,tony-o/rakudo,lucasbuchala/rakudo,sjn/rakudo,tbrowder/rakudo,labster/rakudo,lucasbuchala/rakudo,samcv/rakudo,jonathanstowe/rakudo,labster/rakudo,sjn/rakudo,b2gills/rakudo,nbrown/rakudo,tbrowder/rakudo,Gnouc/rakudo,raydiak/rakudo,salortiz/rakudo,samcv/rakudo,salortiz/rakudo,rakudo/rakudo