Bug#266226: locales: @euro support should again be supported for _all_ euro countries

[Frans Pop <aragorn@tiscali.nl>]

Package: debian-installer
Severity: important

NOTE: I strongly feel this should be fixed before RC2 is released.

HISTORY
=======
With the introduction of the new languagechooser, support for @euro locales 
was lost for a lot of countries which had that support before.
This was noted at the time [1], but ignored because the relevance was unclear.

Now it looks as if proper @euro support _should_ be present [2].

[1] http://lists.debian.org/debian-boot/2004/06/msg01818.html
[2] http://lists.debian.org/debian-boot/2004/08/msg01145.html

PROBLEM
=======
Currently only a few locales have proper @euro support. For these it is set in 
the 3rd field in languagelist in languagechooser, but this solution does not 
work for all relevant language/country combinations.

In languagelist only primary language/country combinations (e.g. French - 
fr_FR@euro, Spanish - es_ES@euro, Catalan - ca_ES@euro) are present, but not 
secondary combinations (e.g. French in Belgium - fr_BE, German in Austria - 
ge_AT).
Currently not even all of the primary combinations have @euro support in 
languagelist (e.g. Dutch - nl_NL, Danish - da_DK).

The current code in the postinst for countrychooser that keeps a suffix if any 
is present in the 3rd field of languagelist could provide a solution for some 
situations, but not for all [a] and even leads to undesired results in other 
situations [b].

[a] English (en_US) does not have a @euro suffix, but en_IR needs one 
[b] AFAICT French in Canada would currently 'inherrit' a @euro suffix
    from fr_FR@euro, but because fr_CA@euro is unsupported the locale
    will fall back to fr_FR@euro even though a fr_CA locale does exist

SOLUTION
========
I think the solution would be to include code (probably in postinst for 
countrychooser).
This script should roughly check whether the previously generated locale 
concerns an euro country, adds the @euro suffix and checks to see if the new 
locale is supported. There would have to be some exceptions e.g. for 
combinations that prefer UTF8 encoding.

Another (maybe the best in the long run) solution could be remove suffixes 
from the languagelist altogether and to have a table in countrychooser of 
preferred locales for any xx_YY combinations where a suffix (or another 
locale than can be automatically generated from the selected language and 
country) is wanted.

The relevant countrycodes for euro are: AT BE DE FI FR GR IR IT LU NL PT SP.