ImproperlyConfigured hidden, which causes hard to debug errors

[Florian Apolloner]

Putting an AppConfig without a name attribute into INSTALLED_APPS raises this nice error:

Traceback (most recent call last):
  File "./manage.py", line 10, in <module>
    execute_from_command_line(sys.argv)
  File "/home/florian/sources/django.git/django/core/management/__init__.py", line 426, in execute_from_command_line
    utility.execute()
  File "/home/florian/sources/django.git/django/core/management/__init__.py", line 418, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/home/florian/sources/django.git/django/core/management/__init__.py", line 280, in fetch_command
    commands = get_commands()
  File "/home/florian/.virtualenvs/conticki/lib/python3.4/functools.py", line 427, in wrapper
    result = user_function(*args, **kwds)
  File "/home/florian/sources/django.git/django/core/management/__init__.py", line 118, in get_commands
    app_configs = apps.get_app_configs()
  File "/home/florian/sources/django.git/django/apps/registry.py", line 121, in get_app_configs
    self.check_ready()
  File "/home/florian/sources/django.git/django/apps/registry.py", line 115, in check_ready
    raise RuntimeError("App registry isn't ready yet.")
RuntimeError: App registry isn't ready yet.

This is due to the fact that d.c.management ignores ImproperlyConfigured from django.setup

[Claude Paroz]

Possible fix

[Aymeric Augustin <aymeric.augustin@…>]

In 2dcde523abe6dca42d9b2d46a47c402979974c77:

Avoided catching ImproperlyConfigured on django.setup().

Fixed #21737. Thanks Florian for the report.

Also removed redundant imports in that file.

[Aymeric Augustin]

Oops - we worked on the same ticket at the same time.

But we came up with pretty much the same solution.

[Claude Paroz]

Thanks, your solution is more elegant.