On 1/26/21, Eryk Sun
The process active code page for GetACP() and GetOEMCP() is changed to UTF-8 (65001). The C runtime also overrides the user locale to UTF-8 if GetACP() returns UTF-8, i.e. setlocale(LC_CTYPE, "") will return "utf8" as the encoding.
One concern is what to do for the special "ansi" and "oem" encodings. If scripts rely on them for IPC, such as with subprocess.Popen(), then it could be frustrating if they're just synonyms for UTF-8 (code page 65001). I've tested that it's possible for Python to peg "ansi" and "oem" to the system ANSI and OEM code pages via GetLocaleInfoEx() with LOCALE_NAME_SYSTEM_DEFAULT and the LCType constants LOCALE_IDEFAULTANSICODEPAGE and LOCALE_IDEFAULTCODEPAGE (OEM). But then they're no longer accurate within the current process, for which ANSI and OEM are UTF-8.