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.

Caused by commit 7737305a

The EmptyResultSet wasn't treated correctly so the end results was
incorrect, too. The bug had been already fixed in master so only tests
added.

There were clauses that weren't needed in the subqueries. These were
ORDER BY, SELECT FOR UPDATE and related selections.

An isnull lookup produced incorrect SQL. This was already fixed
earlier, so only tests added.

Added proxy_models tests by Harm Geerts <github@geertswei.nl>.

Fixed #11892, fixed #16458, fixed #14492.

Proxy __len__ and __contains__ for LazyObject

Python 2.7 allows to combine several 'with' instructions.

Thanks to Collin Anderson for the suggestion and Tim Graham for
reviewing the patch.

Thanks AtomicSpark for the report.

Forwardport of 61283a82 from 1.5.x

Follows 3f2befc9

Thanks clay.evil@ for the suggestion.

Thanks Jug_ for suggestion, john_scott for the initial patch,
and Tim Graham for code review.

In `BoundField.__iter__`, the widget's id attribute is now passed to
each subwidget. A new id_for_label property was added to ChoiceInput.

This is a security fix; disclosure to follow shortly.

This is a security fix; disclosure to follow shortly.

The fix for #20874 caused a MySQL specific failure.

Fixed overflow for the "Recent Actions" widget on the admin index.

Previously the CSS targeted "li.changelink" and therefore didn't
work for the "add" and "delete" actions.

Refs #14868.

Also made some cleanup to build_filter() code by introducing submethods
solve_lookup_type() and prepare_lookup_value().

While using USE_L10N, line numbers and IDs were printed as comma (or
locale equivalent) separated values.

Thanks Kronuz for the report and intial patch.

Fixes #20861.