Impacted versions:
9.0, 10.0

Steps to reproduce:

Create a new database with language English by default and add a new language. Go to settings->translate->languages (in debug mode), inactive English. Go to contacts and "Create". 

Related: https://github.com/odoo/odoo/issues/3854

Current behavior:

Frontend error: Try read en_US language and add to partner, but this not are avalaible.

Expected behavior:
Change default language for all partners.

I need change the default value manually for create new partners:
```
UPDATE public.ir_values
   SET value='S''es_CO''
p1
.'
 WHERE id=1;
```

Video/Screenshot link (optional):


"""Python's strftime supports only the format directives
               that are available on the platform's libc, so in order to
               be 100% cross-platform we map to the directives required by
               the C standard (1989 version), always available on platforms
               with a C standard implementation."""
            
            
            format = format.replace('%-', '%')
            for pattern, replacement in tools.DATETIME_FORMATS_MAP.iteritems():
                format = format.replace(pattern, replacement)
            return str(format)
        conv = locale.localeconv()
        lang_info = {
            'code': lang,
            'iso_code': iso_lang,
            'name': lang_name,
            'active': True,
            'translatable': True,
            'date_format' : fix_datetime_format(locale.nl_langinfo(locale.D_FMT)),
            'time_format' : fix_datetime_format(locale.nl_langinfo(locale.T_FMT)),
            'decimal_point' : fix_xa0(str(conv['decimal_point'])),
            'thousands_sep' : fix_xa0(str(conv['thousands_sep'])),
            'grouping' : str(conv.get('grouping', [])),
        }
        try:
            return self.create(lang_info).id
        finally:
            tools.resetlocale()
    @api.model
    def install_lang(self):