Bug#1021885: apt: please add a command for "give configured $DEFAULTVENDOR mirror"

[Adam Borowski <kilobyte@angband.pl>]

Package: apt
Version: 2.5.3+b1
Severity: wishlist

Hi!
I see that random programs parse apt's configuration to obtain the default
mirror for use with chroots/containers/etc.  And they all do it in their own
hacky and incomplete ways.  Thus eg. piuparts fails to understand 822-style
sources, and so on.

I started looking how to implement that, and went:
 * `apt-cache policy` has that needed information
 * /etc/dpkg/origins/default gives $Vendor
 * ... so the highest-priority entry with "release o=$Vendor" should do
 * but is that o= or l= ?
You see where it is going...

As you acolytes of the Cow know the right way to do so, while me and all
those piudockernetesemu authors don't -- could you please implement
`apt-cache defaultmirror` or such?


Meow!