When I visit http://www.iro.umontreal.ca/contrib/po/maint/tar/ I do not see a listing for no.po (Norwegian), even though http://www2.iro.umontreal.ca/~pinard/po/registry.cgi?domain=tar says that a 'no' translation is available in http://www.iro.umontreal.ca/contrib/po/teams/PO/no/tar-1.13.19.no.po. This translation, however, is byte-for-byte identical to the nb translation http://www.iro.umontreal.ca/contrib/po/teams/PO/nb/tar-1.13.19.nb.po.
In my private copy of GNU tar I am currently using an automated procedure that grabs all translations from http://www.iro.umontreal.ca/contrib/po/maint/tar/. Hence I'm getting 'nb' but not 'no'. Is this the desired behavior? That is, should I advise Norwegian users to set their locale to 'nb' rather than to 'no'?