Impossible to require drupal/coder : consistency issue with the repository

When I try to require drupal/coder from our jFrog repository that points to packagist I get the following error:

[InvalidArgumentException]
 Could not find package drupal/coder. It was however found via repository search, which indicates a consistency issue with the repository.

After some investigations, the URL /artifactory/api/composer/packagist/search.json?q=drupal/coder&type=%type% works as expected and I get the drupal/coder package informations. The URL /artifactory/api/composer/packagist/p/drupal/coder.json works as expected too: I get the package information.

However, the URL /artifactory/api/composer/packagist/p2/drupal/coder.json doesn't work, I get a 404:

{
  "errors": [
    {
      "status": 404,
      "message": "Not Found"
    }
  ]
}

Step to reproduce: 

Create a remote composer repository for Packagist, with the default configuration:

Create the following composer file:

{
    "name": "my/composer-jfrog",
    "authors": [
        {
            "name": "my-name",
            "email": "my-email@example.com"
        }
    ],
    "require": {},
    "repositories": [
        {
            "type": "composer",
            "url": "<url-to-jfrog>/artifactory/api/composer/packagist"
        },
        {
            "packagist.org": false
        }
    ]
}

Then run

composer require drupal/coder