To have a more logic block, we fill the gaps in the ::1-::19 series with hexadecimal ones.
Furthermore, currently, Debian tends to select last added address,
currently inet6 2001:470:1f13:896::16 (at the top of ifconfig).
Aliases are now RFC 3484 compliant with preferred_lft set at 0, so
it will normally prefer the canonical eglide.org ::code:15:11fe one.