Bug#239560: base-config: Set default mirror site patch

[Christian Perrier <bubulle@debian.org>]

Quoting Kenshi Muto (kmuto@debian.org):

> Well, I found iso_3166.tab in iso-codes causes trouble apt-setup.
> 
> iso_3166.tab in iso-codes includes "," with country name (such as
> "Korea, Republic of" or "Congo, The Democratic Republic of").
> Current apt-setup makes debconf choices from these names, but ","
> confuses it.
> 
> iso3166.tab in libc6 doesn't include "," (at least this time), so
> this problem doesn't become.

Yeah, I had to first "sed 's/,/;/g'" in countrychooser for avoiding this.

iso_3166.tab from iso-codes has the official names for countries, some
of which use commas....so we have to deal with this as iso_3166.tab
cannot be changed.