homepage

In the C code, sys.flags.isolated clearly documented as linked to the -I option:
static PyStructSequence_Field flags_fields[] = {
 {"debug", "-d"},
 {"inspect", "-i"},
 {"interactive", "-i"},
 {"optimize", "-O or -OO"},
 {"dont_write_bytecode", "-B"},
 {"no_user_site", "-s"},
 {"no_site", "-S"},
 {"ignore_environment", "-E"},
 {"verbose", "-v"},
 /* {"unbuffered", "-u"}, */
 /* {"skip_first", "-x"}, */
 {"bytes_warning", "-b"},
 {"quiet", "-q"},
 {"hash_randomization", "-R"},
 {"isolated", "-I"},
 {"dev_mode", "-X dev"},
 {"utf8_mode", "-X utf8"},
 {0}
};
> The only thing here is that '-I' returns '-s -E -I' unlike other options where args can be used for comparison logic in check_options.
I expect to get:
$ python3 -I -c 'import subprocess; print(subprocess._args_from_interpreter_flags())'
['-I']
instead of:
['-s', '-E']
-I is different from -s -E: it also avoids to add the script directory or an empty string to sys.path.