Restore exact behaviour of List.index/indices/contains
Restore exact behaviour of List.index/indices/contains

With c9b0218544 a warning is issued with regards to using a List
as a string, when that is most likely not what one wants.  However,
that commit also changed the string on which the method operates
for a list like <a b c> from "a b c" to "abc".  This commit restores
the "a b c" behaviour.

tbrowder/rakudo,rakudo/rakudo,nbrown/rakudo,labster/rakudo,rakudo/rakudo,rakudo/rakudo,salortiz/rakudo,labster/rakudo,tony-o/rakudo,salortiz/rakudo,tbrowder/rakudo,rakudo/rakudo,MasterDuke17/rakudo,tbrowder/rakudo,nbrown/rakudo,softmoth/rakudo,tony-o/rakudo,softmoth/rakudo,salortiz/rakudo,salortiz/rakudo,MasterDuke17/rakudo,softmoth/rakudo,nbrown/rakudo,rakudo/rakudo,tbrowder/rakudo,tony-o/rakudo,labster/rakudo,tbrowder/rakudo,nbrown/rakudo,salortiz/rakudo,MasterDuke17/rakudo,tony-o/rakudo,nbrown/rakudo,labster/rakudo,nbrown/rakudo,MasterDuke17/rakudo,salortiz/rakudo,labster/rakudo,tony-o/rakudo,softmoth/rakudo,softmoth/rakudo,MasterDuke17/rakudo,MasterDuke17/rakudo,rakudo/rakudo,tbrowder/rakudo,labster/rakudo,tony-o/rakudo