title: composer cannot find my installed package
body: <p>I have a package in a private github repository.</p>
  
  <p>When I run <code>composer require my_vendor/my_package</code> the package gets added to composer.json and shows up in the vendor directory.</p>
  
  <p>When I run <code>composer remove my_vendor/my_package</code> it gives me a warning:  </p>
  
  <blockquote>
    <p>Package "my_vendor/my_package" listed for update is not installed.
    Ignoring.</p>
  </blockquote>
  
  <p>So when I run <code>composer prohibits my_vendor/my_package</code> it says</p>
  
  <blockquote>
    <p>Could not find package "my_vendor/my_package" in your project</p>
  </blockquote>
  
  <p>If I run <code>composer show</code> (after requiring the package) it is not displayed in the list. </p>
  
  <p>This package has a dependency (lexik/authenticationbundle) which is correctly installed, removed and show in list of installed packages (but not listed in the tree view since it is a dependency of a non existent package)...</p>
  
  <p>I have no clue on what could explain this behavior.</p>
  
  <p>Any suggestion?</p>
  
  <p><strong>edit</strong> (adding composer.json content)</p>
  
  <pre><code>{
      "type": "project",
      "license": "proprietary",
      "require": {
          "php": "^7.1.3",
          "ext-ctype": "*",
          "ext-iconv": "*",
          "api-platform/api-pack": "^1.1",
          "composer/composer": "^1.6",
          "symfony/console": "^4.1",
          "symfony/flex": "^1.0",
          "symfony/framework-bundle": "^4.1",
          "symfony/lts": "^4@dev",
          "symfony/orm-pack": "^1.0",
          "symfony/web-server-bundle": "^4.1",
          "symfony/yaml": "^4.1"
      },
      "require-dev": {
          "symfony/dotenv": "^4.1"
      },
      "repositories": [
          {
              "type": "vcs",
              "url": "https://github.com/my_repo/my_package.git"
          }
      ],
      "config": {
          "preferred-install": {
              "*": "dist"
          },
          "sort-packages": true
      },
      "autoload": {
          "psr-4": {
              "App\\": "src/"
          }
      },
      "autoload-dev": {
          "psr-4": {
              "App\\Tests\\": "tests/"
          }
      },
      "replace": {
          "symfony/polyfill-ctype": "*",
          "symfony/polyfill-iconv": "*",
          "symfony/polyfill-php71": "*",
          "symfony/polyfill-php70": "*",
          "symfony/polyfill-php56": "*"
      },
      "scripts": {
          "auto-scripts": {
              "assets:install %PUBLIC_DIR%": "symfony-cmd",
              "cache:clear": "symfony-cmd"
          },
          "post-install-cmd": [
              "@auto-scripts"
          ],
          "post-package-install": [
              "App\\Utility\\Bootstrap\\Setup::execute",
              "@auto-scripts"
          ],
          "pre-package-uninstall": [
              "App\\Utility\\Bootstrap\\Demolish::execute",
              "@auto-scripts"
          ]
      },
      "conflict": {
          "symfony/symfony": "*"
      },
      "extra": {
          "symfony": {
              "id": "01C1K60FQVPP7FCAC3YB6639RZ",
              "allow-contrib": true
          }
      }
  }
  </code></pre>
  
  <p>Furthermore, creating a new project and requiring the package correctly adds it to the list of installed packages, thus removing it works fine. Then I tried to delete lock file and running a composer update and eventually I tried to require/remove it but with no luck.</p>