Matej Cepl <report@bugs.python.org> wrote:
> >>> import locale
> >>> locale.localeconv()
> {'p_cs_precedes': 127, 'n_sep_by_space': 127, 'n_sign_posn': 127, 'n_cs_precedes': 127, 'grouping': [], 'positive_sign': '', 'mon_grouping': [], 'p_sep_by_space': 127, 'mon_thousands_sep': '', 'currency_symbol': '', 'mon_decimal_point': '', 'int_curr_symbol': '', 'thousands_sep': '', 'frac_digits': 127, 'int_frac_digits': 127, 'negative_sign': '', 'decimal_point': '.', 'p_sign_posn': 127}
> >>> locale.setlocale(locale.LC_ALL, '')
> 'LC_CTYPE=en_US.utf8;LC_NUMERIC=en_IE.utf8;LC_TIME=en_IE.utf8;LC_COLLATE=en_US.utf8;LC_MONETARY=en_IE.utf8;LC_MESSAGES=en_US.utf8;LC_PAPER=en_IE.utf8;LC_NAME=en_US.utf8;LC_ADDRESS=en_US.utf8;LC_TELEPHONE=en_US.utf8;LC_MEASUREMENT=en_IE.utf8;LC_IDENTIFICATION=en_US.utf8'
> >>> locale.localeconv()
> {'p_cs_precedes': 1, 'n_sep_by_space': 0, 'n_sign_posn': 1, 'n_cs_precedes': 1, 'grouping': [3, 3, 0], 'positive_sign': '', 'mon_grouping': [3, 3, 0], 'p_sep_by_space': 0, 'mon_thousands_sep': ',', 'currency_symbol': '€', 'mon_decimal_point': '.', 'int_curr_symbol': 'EUR ', 'thousands_sep': ',', 'frac_digits': 2, 'int_frac_digits': 2, 'negative_sign': '-', 'decimal_point': '.', 'p_sign_posn': 1}

These look normal.  I'm puzzled, because that's what is going on in the test
as well.  Do you get the failure when running the test in isolation:

./python -m test test_format

If this passes, there might be some interaction with other tests.

If it doesn't pass, I would step through the test in gdb (break PyLocale_localeconv)
and see which member of struct lconv is the troublemaker.