TYPO3 Core

Currently the composer.json has to have a replace configuration which tells composer to remove the vendor.

Now this is deprecated in composer 2.0, which will be around sometime in the future (probably) and therefore there should be a solution for this issue.

Clearly this does not affect the installation when adding a package through composer require, but for example, when working in an isolated testing environment where you may have to `compsoer install` based on a single package to get the necessary dependencies, compsoer might break at some point.

The warning looks like this:
Deprecation warning: replace.ext_name is invalid, it should have a vendor name, a forward slash, and a package name. The vendor and package name can be words separated by -, . or _. The complete name should match "[a-z0-9]([_.-]?[a-z0-9]+)*/[a-z0-9]([_.-]?[a-z0-9]+)*". Make sure you fix this as Composer 2.0 will error.

In order to achieve this, I believe the typo3/cms-composer-installers has to be updated.

The current behaviour is that if you have an extension with replace, the extension will be copied to typo3conf/ext/ext_ext_name.