ResolverMatch.app_name doesn't contain full application namespace for nested namespaces

[Marten Kenbeek]

ResolverMatch.app_name only contains the outer-most application namespace in the case of nested namespaces. It should contain the full namespace path, separated by :, just like ResolverMatch.namespace.

The documentation[1] is a bit ambiguous in this regard, but I was very much surprised when I found out this behaviour, and in my opinion it's a very obvious bug. The only internal use[2 and 3] would currently be incorrect in the case of nested namespaces. If it should instead follow the backwards compatibility guidelines because of the ambiguity in the docs, please mark it as such.

[1] ​https://docs.djangoproject.com/en/1.8/ref/urlresolvers/#django.core.urlresolvers.ResolverMatch.app_name
[2] ​https://github.com/django/django/blob/master/django/contrib/admin/options.py#L897
[3] ​https://github.com/django/django/blob/master/django/contrib/admin/templatetags/admin_urls.py#L38

[Tim Graham]

Documenting in the release notes how to update your code for this "bug fix" is likely sufficient.

[Marten Kenbeek]

PR: ​https://github.com/django/django/pull/4771

[Tim Graham <timograham@…>]

In bc77eb6:

Fixed #24906 -- Fixed ResolverMatch.app_name for nested namespaces.

Set ResolverMatch.app_name to the full path of nested application
namespaces.