Enbase is not working correctly with series not at head for base 64

[Oldes]

This is OK:

>> x: #{FF00FF00} debase/base enbase/base next x 2 2
== #{00FF00}

but this is not:

>> x: #{FF00FF00} debase enbase next x
== #{FF00FF}

Here is fix I did in my brench: https://github.com/Oldes/Rebol3/commit/767fd06dabf122a4a36bec4b44cd2611233193f4