--no-scripts removes dev dependencies

[cuchac]

Hello,
when I run composer update dev dependencies are installed and appears in lock file. When I run composer update --no-scripts dev dependencies are removed from lock file and uninstalled.

Example repository

composer.json

{
  "require": {
    "wikimedia/composer-merge-plugin": "^2.0"
  },
  "extra": {
    "merge-plugin": {
      "require": [
        "composer-shared.json"
      ],
      "merge-extra": true,
      "merge-scripts": true
    }
  }
}

composer-shared.json

{
  "require": {
  },
  "require-dev": {
    "phpunit/phpunit": "^7.5"
  }
}