“Python invisibly aborts the loading of additional cookies inside SimpleCookie.load() as soon as it encounters one it doesn’t understand.”
A JSON cookie that every browser accepted broke Go’s standard library and cascaded up the stack. Firefox, Chrome and Safari each accept different characters, and Safari keeps the cookie up to the bad character instead of dropping it as the RFC says. In Python one malformed cookie set by a subdomain can wipe out every cookie for the whole site. The spec dates to 1997 and still nobody parses it the same way.