Issue #2345969 by webflo, mauzeh: Fixed Keep English during installation.

core/includes/install.core.inc

@@ -1566,7 +1566,9 @@ function install_download_additional_translations_operations(&$install_state) {
   if ($langcode != 'en') {
     \Drupal::config('system.site')->set('langcode', $langcode)->save();
     \Drupal::service('language.default')->set($language);
-    entity_delete_multiple('configurable_language', array('en'));
+    if (empty($install_state['profile_info']['keep_english'])) {
+      entity_delete_multiple('configurable_language', array('en'));
+    }
   }
 
   // If there is more than one language or the single one is not English, we

core/modules/system/src/Tests/Installer/InstallerTranslationMultipleLanguageKeepEnglishTest.php

+<?php
+
+/**
+ * @file
+ * Contains \Drupal\system\Tests\Installer\InstallerTranslationMultipleLanguageForeignTest.
+ */
+
+namespace Drupal\system\Tests\Installer;
+use Drupal\simpletest\InstallerTestBase;
+
+/**
+ * Tests translation files for multiple languages get imported during install.
+ *
+ * @group Installer
+ */
+class InstallerTranslationMultipleLanguageKeepEnglishTest extends InstallerTestBase {
+
+  /**
+   * Overrides the language code in which to install Drupal.
+   *
+   * @var string
+   */
+  protected $langcode = 'de';
+
+  /**
+   * Switch to the multilingual testing profile
+   *
+   * @var string
+   */
+  protected $profile = 'testing_multilingual';
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUpLanguage() {
+    // Place custom local translations in the translations directory.
+    mkdir(DRUPAL_ROOT . '/' . $this->siteDirectory . '/files/translations', 0777, TRUE);
+    file_put_contents(DRUPAL_ROOT . '/' . $this->siteDirectory . '/files/translations/drupal-8.0.0.de.po', "msgid \"\"\nmsgstr \"\"\nmsgid \"Save and continue\"\nmsgstr \"Save and continue German\"");
+    file_put_contents(DRUPAL_ROOT . '/' . $this->siteDirectory . '/files/translations/drupal-8.0.0.es.po', "msgid \"\"\nmsgstr \"\"\nmsgid \"Save and continue\"\nmsgstr \"Save and continue Spanish\"");
+
+    parent::setUpLanguage();
+    $this->translations['Save and continue'] = 'Save and continue German';
+  }
+
+  /**
+   * Tests that English is still present.
+   */
+  public function testKeepEnglish() {
+    $this->assertTrue((bool) \Drupal::languageManager()->getLanguage('en'), 'English is present.');
+  }
+
+}

core/profiles/testing_multilingual/testing_multilingual.info.yml

@@ -6,3 +6,4 @@ core: 8.x
 hidden: true
 dependencies:
   - locale
+keep_english: true