With your patch Martin, test_nonascii is skipped on Android when LANG is not set and the issue is fixed.

> Just to clarify, is the problem that Python (correctly) assumes UTF-8 encoding on Android, but Readline does not unless you tweak the environment variable?

Readline (correctly) uses the locale environment variables to set eight-bit mode (see function _rl_init_eightbit() in Readline nls.c) and when the LC_CTYPE category is C or POSIX, eight-bit characters are discarded on input and a bell character ('\x07') is echoed instead.