`get_deleted_objects` causes an error if there is no change view.

[Keryn Knight <django@…>]

The ​format_callback used for rendering the objects to be deleted on the confirmation screen doesn't attempt to fail gracefully, if there is no named URL fitting the "namespace:appname_modelname_change" - if get_urls() is overridden on a ModelAdmin subclass to either change, remove or replace the change_view, the delete page will never work due to a NoReverseMatch.

Proposed solution: NoReverseMatch should be caught, and the format should end up the same as if has_admin were False.

(note: link to GitHub above is to the latest revision in master, as I write this.)

[Rainer Koirikivi]

Created a test project and verified that the bug occurs.

[Rainer Koirikivi]

Active work on this at: ​https://github.com/koirikivi/django/tree/ticket_20640
Pull request: ​https://github.com/django/django/pull/1485
Tests pass under postgresql and sqlite

[Rainer Koirikivi]

Related issue (NoReverseMatch in changelist_view if the "namespace:appname_modelname_change" url is removed): #20934

[Tim Graham <timograham@…>]

In 3c0300405009b82b52fd15483371097221662fcd:

Fixed #20640 -- Avoided NoReverseMatch in get_deleted_objects

The default delete action resulted in a NoReverseMatch if it were to
list any Model with a ModelAdmin with get_urls overridden to remove
the change url. Catching the error and not displaying the link in that
case, as was already done for models with no registered admins.

Thanks Keryn Knight for the report.