Some more corner case fixes in Str.split()
Some more corner case fixes in Str.split()

++ for writing tests!

labster/rakudo,dankogai/rakudo,samcv/rakudo,ugexe/rakudo,softmoth/rakudo,raydiak/rakudo,tony-o/rakudo,ugexe/rakudo,labster/rakudo,rakudo/rakudo,tbrowder/rakudo,awwaiid/rakudo,tbrowder/rakudo,LLFourn/rakudo,azawawi/rakudo,awwaiid/rakudo,tony-o/rakudo,Gnouc/rakudo,ungrim97/rakudo,labster/rakudo,salortiz/rakudo,dankogai/rakudo,rakudo/rakudo,LLFourn/rakudo,ugexe/rakudo,zostay/rakudo,awwaiid/rakudo,nbrown/rakudo,labster/rakudo,salortiz/rakudo,paultcochrane/rakudo,dankogai/rakudo,ungrim97/rakudo,raydiak/rakudo,MasterDuke17/rakudo,usev6/rakudo,sjn/rakudo,lucasbuchala/rakudo,b2gills/rakudo,ab5tract/rakudo,b2gills/rakudo,awwaiid/rakudo,Gnouc/rakudo,LLFourn/rakudo,ab5tract/rakudo,rakudo/rakudo,tbrowder/rakudo,ab5tract/rakudo,jonathanstowe/rakudo,paultcochrane/rakudo,rakudo/rakudo,jonathanstowe/rakudo,jonathanstowe/rakudo,Gnouc/rakudo,nbrown/rakudo,ugexe/rakudo,samcv/rakudo,nbrown/rakudo,tony-o/rakudo,tbrowder/rakudo,tony-o/rakudo,zostay/rakudo,dankogai/rakudo,usev6/rakudo,nbrown/rakudo,sjn/rakudo,nbrown/rakudo,lucasbuchala/rakudo,softmoth/rakudo,paultcochrane/rakudo,jonathanstowe/rakudo,b2gills/rakudo,usev6/rakudo,Gnouc/rakudo,paultcochrane/rakudo,usev6/rakudo,ungrim97/rakudo,LLFourn/rakudo,usev6/rakudo,lucasbuchala/rakudo,b2gills/rakudo,nbrown/rakudo,zostay/rakudo,ungrim97/rakudo,b2gills/rakudo,sjn/rakudo,tony-o/rakudo,samcv/rakudo,azawawi/rakudo,raydiak/rakudo,MasterDuke17/rakudo,zostay/rakudo,MasterDuke17/rakudo,samcv/rakudo,MasterDuke17/rakudo,Gnouc/rakudo,awwaiid/rakudo,ab5tract/rakudo,labster/rakudo,samcv/rakudo,MasterDuke17/rakudo,lucasbuchala/rakudo,azawawi/rakudo,salortiz/rakudo,salortiz/rakudo,Gnouc/rakudo,labster/rakudo,azawawi/rakudo,salortiz/rakudo,raydiak/rakudo,rakudo/rakudo,azawawi/rakudo,sjn/rakudo,softmoth/rakudo,ungrim97/rakudo,tbrowder/rakudo,softmoth/rakudo,salortiz/rakudo,sjn/rakudo,MasterDuke17/rakudo,tbrowder/rakudo,LLFourn/rakudo,dankogai/rakudo,tony-o/rakudo,lucasbuchala/rakudo,ab5tract/rakudo,rakudo/rakudo,softmoth/rakudo,paultcochrane/rakudo,jonathanstowe/rakudo,ugexe/rakudo