Dear Maintainer,

It would be nict to have the ability to reference a Debian version also by its
major number (e.g. 10) and not only by its name (e.g. buster) in sources.list.

E.g. right now `/etc/apt/sources.list` looks like this:

deb http://deb.debian.org/debian/ buster main non-free contrib

It should be possible to use `10` instead of `buster`:

deb http://deb.debian.org/debian/ 10 main non-free contrib


For those who do not know/remember the chronological sequence of the version
names - numbers tell more. It's also allows for a more neutral style - as not
everybody might like things like `potato` or `etch`...

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