* Fix incorrect assertion in TestSystemCheck
It only worked by accident, due to the definition of equality on block objects.
* Explicitly cast child_blocks.items() to a list when deconstructing blocks
The result of items() is a lazily-evaluated ItemsView object, which Django's deep_deconstruct function (used to detect changes for migrations) doesn't recognise; as a result, the blocks inside it don't get deconstructed. Luckily, this doesn't break migration change detection, because we define __eq__ on Block so that two blocks with matching definitions are considered equal. Nevertheless, it's best that we don't rely on that behaviour; it was only implemented originally as a workaround for https://code.djangoproject.com/ticket/24340 in Django <1.9 (where deep_deconstruct didn't recurse into lists either).
* Bring comment for Block.__eq__ up to date
* Issue 4334: Excluded fields are also excluded when a panel set is explicitly defined on a model.
* Improved notation after review with @BertrandBordage
* Incorrect field name in comment
I'd like to propose removing the shims for IE6-9 from the project template.
The rationale for this is the same as for dropping support for EOL version of Django, etc. - i.e., these versions of Internet Explorer are no longer supported by the vendor (the last version of Windows that you cannot upgrade to use IE10 or higher was Windows XP, which reached end of life in 2014).
On that basis I think that Wagtail should not include these shims by default - projects that for whatever reason still need to support these browsers can easily add them to their templates.
Previously the validators were run against empty user models, which made
the UserAttributeSimilarityValidator accept passwords that would
otherwise have been rejected.
Tests have been added to ensure the validator run correctly.
This change copies the Wagtail admin favicon.ico (from
wagtail/admin/static_src/wagtailadmin/images) into the Sphinx build
directory so that built docs use the same favicon as the admin.
Makes use of [the Sphinx `html_favicon` setting](http://www.sphinx-doc.org/en/1.5.1/config.html#confval-html_favicon)
which adds this line to the generated HTML:
```html
<link rel="shortcut icon" href="_static/favicon.ico"/>
```
Fixes #4340.
