The $class variable gets overwritten in the function.
This causes error messages to be less helpful. For example if you setup a has_many but forget the has_one on the other side the error will look something like
`[Emergency] Uncaught Exception: No has_one found on class 'SomeObject', the has_many relation from 'SilverStripe\View\ViewableData' to 'SomeObject' requires a has_one on 'SomeObject'`
fixing this gives a more useful error, like
`[Emergency] Uncaught Exception: No has_one found on class 'SomeObject', the has_many relation from 'Page' to 'SomeObject' requires a has_one on 'SomeObject'`
When modules are installed as the webroot,
manifest generation should behave the same way as when they're in a subfolder.
Which means accepting the module folder both with a _config/ folder
and a _config.php file present.
Note that our usage of `$asSingleton` in `get()` is fine. Quote from the PSR:
> Two successive calls to get with the same identifier SHOULD return the same value. However, depending on the implementor design and/or user configuration, different values might be returned, so user SHOULD NOT rely on getting the same value on 2 successive calls.
Regression introduced through https://github.com/silverstripe/silverstripe-framework/issues/6362.
Quote from the RFC:
```
Thus the order of action precedence becomes
action callback
action on the Form
action on the FormRequestHandler
action on any parent controller (if given)
```
* Test databases now include timestamp for easier debugging
* Use classname::class instead of string literal classnames
* Remove DataObject::get_one() from SapphireTest
* More fixes to ICU DB inconsitency for time formatting
* Correctly restore PHPUnits error handler
FIX for #4417: Ensuring ->removeValidation() is defined on instances of Validator. Setup new API for enabling/disabling validation. Documentation and better type handling.
Prevent html errors when FormField::create_tag('meta') is called from $MetaTags() so
```
<meta name="generator" content="SilverStripe - http://silverstripe.org"></meta>
```
becomes
```
<meta name="generator" content="SilverStripe - http://silverstripe.org" />
```
Add all void elements to list
* API Implement InheritedPermission calculator
* API Rename RootPermissions to DefaultPermissionChecker
API Refactor inherited permission fields into InheritedPermissionExtension
API Introduce PermissionChecker interface
