title: Issue with Composer install of Semantic MediaWiki
body: <p>I have a new (installed yesterday) installation of MediaWiki and am trying to install the Semantic MediaWiki plugin.</p>
  
  <p>I tried following the instructions at <a href="https://www.mediawiki.org/wiki/Composer#Using_composer-merge-plugin" rel="nofollow noreferrer">mediawiki</a>, but here's what happened when I tried to install composer-merge-plugin:</p>
  
  <pre><code>$ composer require wikimedia/composer-merge-plugin
  Using version ^1.3 for wikimedia/composer-merge-plugin
  ./composer.json has been updated
  &gt; ComposerHookHandler::onPreUpdate
  Loading composer repositories with package information
  Updating dependencies (including require-dev)
  Your requirements could not be resolved to an installable set of packages.
  
    Problem 1
      - remove mediawiki/core No version set (parsed as 1.0.0)|remove mediawiki/semantic-media-wiki 2.4.6
      - don't install mediawiki/semantic-media-wiki 2.4.6|remove mediawiki/core No version set (parsed as 1.0.0)
      - Installation request for mediawiki/core No version set (parsed as 1.0.0) -&gt; satisfiable by mediawiki/core[No version set (parsed as 1.0.0)].
      - Installation request for mediawiki/semantic-media-wiki (installed at 2.4.6, required as &gt;=2.4) -&gt; satisfiable by mediawiki/semantic-media-wiki[2.4.6].
  
  
  Installation failed, reverting ./composer.json to its original content.
  </code></pre>
  
  <p>So instead, I just edited composer.local.json to the following:</p>
  
  <pre><code>{
      "require": {
          "mediawiki/sub-page-list": "&gt;=1.0",
          "mediawiki/semantic-media-wiki": "&gt;=2.4"
      },
      "extra": {
          "merge-plugin": {
              "include": [
                  "extensions/*/composer.json",
                  "skins/*/composer.json"
              ]
          }
      }
  }
  </code></pre>
  
  <p>and ran <code>composer update</code>. I get a similar error:</p>
  
  <pre><code>$ composer update
  &gt; ComposerHookHandler::onPreUpdate
  Loading composer repositories with package information
  Updating dependencies (including require-dev)
  Your requirements could not be resolved to an installable set of packages.
  
    Problem 1
      - remove mediawiki/core No version set (parsed as 1.0.0)|remove mediawiki/semantic-media-wiki 2.4.6
      - don't install mediawiki/semantic-media-wiki 2.4.0|remove mediawiki/core No version set (parsed as 1.0.0)
      - don't install mediawiki/semantic-media-wiki 2.4.1|remove mediawiki/core No version set (parsed as 1.0.0)
      - don't install mediawiki/semantic-media-wiki 2.4.2|remove mediawiki/core No version set (parsed as 1.0.0)
      - don't install mediawiki/semantic-media-wiki 2.4.3|remove mediawiki/core No version set (parsed as 1.0.0)
      - don't install mediawiki/semantic-media-wiki 2.4.4|remove mediawiki/core No version set (parsed as 1.0.0)
      - don't install mediawiki/semantic-media-wiki 2.4.5|remove mediawiki/core No version set (parsed as 1.0.0)
      - don't install mediawiki/semantic-media-wiki 2.4.6|remove mediawiki/core No version set (parsed as 1.0.0)
      - Installation request for mediawiki/core No version set (parsed as 1.0.0) -&gt; satisfiable by mediawiki/core[No version set (parsed as 1.0.0)].
      - Installation request for mediawiki/semantic-media-wiki &gt;=2.4 -&gt; satisfiable by mediawiki/semantic-media-wiki[2.4.0, 2.4.1, 2.4.2, 2.4.3, 2.4.4, 2.4.5, 2.4.6].
  </code></pre>
  
  <p>The instructions at <a href="https://www.semantic-mediawiki.org/wiki/Help:Installation/Using_Composer_with_MediaWiki_1.25%2B#scite-7310ad6839b15c4be0c28f56f1313cbf" rel="nofollow noreferrer">senamtic mediawiki</a> gives a similar error:</p>
  
  <pre><code>$ composer require mediawiki/semantic-media-wiki "~2.4" --update-no-dev
  ./composer.json has been updated
  &gt; ComposerHookHandler::onPreUpdate
  Loading composer repositories with package information
  Updating dependencies
  Your requirements could not be resolved to an installable set of packages.
  
    Problem 1
      - remove mediawiki/core No version set (parsed as 1.0.0)|remove mediawiki/semantic-media-wiki 2.4.6
      - don't install mediawiki/semantic-media-wiki 2.4.0|remove mediawiki/core No version set (parsed as 1.0.0)
      - don't install mediawiki/semantic-media-wiki 2.4.1|remove mediawiki/core No version set (parsed as 1.0.0)
      - don't install mediawiki/semantic-media-wiki 2.4.2|remove mediawiki/core No version set (parsed as 1.0.0)
      - don't install mediawiki/semantic-media-wiki 2.4.3|remove mediawiki/core No version set (parsed as 1.0.0)
      - don't install mediawiki/semantic-media-wiki 2.4.4|remove mediawiki/core No version set (parsed as 1.0.0)
      - don't install mediawiki/semantic-media-wiki 2.4.5|remove mediawiki/core No version set (parsed as 1.0.0)
      - don't install mediawiki/semantic-media-wiki 2.4.6|remove mediawiki/core No version set (parsed as 1.0.0)
      - Installation request for mediawiki/core No version set (parsed as 1.0.0) -&gt; satisfiable by mediawiki/core[No version set (parsed as 1.0.0)].
      - Installation request for mediawiki/semantic-media-wiki ~2.4 -&gt; satisfiable by mediawiki/semantic-media-wiki[2.4.0, 2.4.1, 2.4.2, 2.4.3, 2.4.4, 2.4.5, 2.4.6].
  
  
  Installation failed, reverting ./composer.json to its original content.
  </code></pre>
  
  <p>I haven't done anything to composer.json, but for completeness:</p>
  
  <pre><code>{
  "name": "mediawiki/core",
          "description": "Free software wiki application developed by the Wikimedia Foundation and others",
          "keywords": ["mediawiki", "wiki"],
          "homepage": "https://www.mediawiki.org/",
          "authors": [
                  {
                          "name": "MediaWiki Community",
                          "homepage": "https://www.mediawiki.org/wiki/Special:Version/Credits"
                  }
          ],
          "license": "GPL-2.0+",
          "support": {
                  "issues": "https://bugs.mediawiki.org/",
                  "irc": "irc://irc.freenode.net/mediawiki",
                  "wiki": "https://www.mediawiki.org/"
          },
          "require": {
                  "composer/semver": "1.4.2",
                  "cssjanus/cssjanus": "1.1.2",
                  "ext-ctype": "*",
                  "ext-iconv": "*",
                  "ext-json": "*",
                  "ext-mbstring": "*",
                  "ext-xml": "*",
                  "liuggio/statsd-php-client": "1.0.18",
                  "mediawiki/at-ease": "1.1.0",
                  "oojs/oojs-ui": "0.17.10",
                  "oyejorge/less.php": "1.7.0.10",
                  "php": "&gt;=5.5.9",
                  "psr/log": "1.0.0",
                  "wikimedia/assert": "0.2.2",
                  "wikimedia/base-convert": "1.0.1",
                  "wikimedia/cdb": "1.4.1",
                  "wikimedia/cldr-plural-rule-parser": "1.0.0",
                  "wikimedia/composer-merge-plugin": "1.3.1",
                  "wikimedia/html-formatter": "1.0.1",
                  "wikimedia/ip-set": "1.1.0",
                  "wikimedia/php-session-serializer": "1.0.4",
                  "wikimedia/relpath": "1.0.3",
                  "wikimedia/running-stat": "1.1.0",
                  "wikimedia/scoped-callback": "1.0.0",
                  "wikimedia/utfnormal": "1.1.0",
                  "wikimedia/wait-condition-loop": "1.0.1",
                  "wikimedia/wrappedstring": "2.2.0",
                  "zordius/lightncandy": "0.23"
          },
          "require-dev": {
                  "composer/spdx-licenses": "1.1.4",
                  "jakub-onderka/php-parallel-lint": "0.9.2",
                  "justinrainbow/json-schema": "~3.0",
                  "mediawiki/mediawiki-codesniffer": "0.7.2",
                  "monolog/monolog": "~1.18.2",
                  "nikic/php-parser": "2.1.0",
                  "nmred/kafka-php": "0.1.5",
                  "phpunit/phpunit": "4.8.24",
                  "wikimedia/avro": "1.7.7"
          },
          "suggest": {
                  "ext-apc": "Local data and opcode cache",
                  "ext-fileinfo": "Improved mime magic detection",
                  "ext-intl": "ICU integration",
                  "ext-wikidiff2": "Diff accelerator",
                  "monolog/monolog": "Flexible debug logging system",
                  "nmred/kafka-php": "Send debug log events to kafka",
                  "pear/mail": "Mail sending support",
                  "pear/mail_mime": "Mail sending support",
                  "pear/mail_mime-decode": "Mail sending support",
                  "wikimedia/avro": "Binary serialization format used with kafka"
          },
          "autoload": {
                  "psr-0": {
                          "ComposerHookHandler": "includes/composer"
                  }
          },
          "scripts": {
                  "lint": "parallel-lint --exclude vendor",
                  "phpcs": "phpcs -p -s",
                  "fix": "phpcbf",
                  "pre-install-cmd": "ComposerHookHandler::onPreInstall",
                  "pre-update-cmd": "ComposerHookHandler::onPreUpdate",
                  "test": [
                          "composer lint",
                          "composer phpcs"
                  ]
          },
          "config": {
                  "optimize-autoloader": true,
                  "prepend-autoloader": false
          },
          "extra": {
                  "merge-plugin": {
                          "include": [
                                  "composer.local.json"
                          ],
                          "merge-dev": false
                  }
          }
  }
  </code></pre>
  
  <p>Also, why does it look like it's trying to remove mediawiki/core?</p>