Creating superuser generates exception when system locale is not set

[chomik]

When trying to create superuser with system locale not set (either when syncing db for the first time or invoking manage.py createsuperuser) an exception is rised:

Traceback (most recent call last):
  File "../manage.py", line 9, in <module>
    execute_from_command_line(sys.argv)
  File "/Users/neaf/sprint/django/django/core/management/__init__.py", line 419, in execute_from_command_line
    utility.execute()
  File "/Users/neaf/sprint/django/django/core/management/__init__.py", line 358, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/Users/neaf/sprint/django/django/core/management/base.py", line 196, in run_from_argv
    self.execute(*args, **options.__dict__)
  File "/Users/neaf/sprint/django/django/core/management/base.py", line 232, in execute
    output = self.handle(*args, **options)
  File "/Users/neaf/sprint/django/django/contrib/auth/management/commands/createsuperuser.py", line 63, in handle
    default_username = get_default_username()
  File "/Users/neaf/sprint/django/django/contrib/auth/management/__init__.py", line 105, in get_default_username
    default_username = get_system_username()
  File "/Users/neaf/sprint/django/django/contrib/auth/management/__init__.py", line 85, in get_system_username
    return getpass.getuser().decode(locale.getdefaultlocale()[1])
TypeError: decode() argument 1 must be string, not None

[chomik]

suggested solution

[chomik]

test improvement

[Łukasz Rekucki]

Duplicate of #16017, #17185, #17022.