diff --git a/core/lib/Drupal/Core/Extension/ExtensionList.php b/core/lib/Drupal/Core/Extension/ExtensionList.php
index 6e78072..c9a2736 100644
--- a/core/lib/Drupal/Core/Extension/ExtensionList.php
+++ b/core/lib/Drupal/Core/Extension/ExtensionList.php
@@ -106,6 +106,10 @@ public function __construct($root, $type, CacheBackendInterface $cache, InfoPars
   public function reset() {
     $this->extensions = NULL;
     $this->cache->delete($this->getCacheId());
+    $this->extensionInfo = NULL;
+    $this->cache->delete("system.{$this->type}.info");
+    $this->fileNames = NULL;
+    \Drupal::state()->delete("system.{$this->type}.files");
     return $this;
   }
 
@@ -166,11 +170,7 @@ public function listExtensions() {
       return $extensions;
     }
     $extensions = $this->doListExtensions();
-    $this->cache->get($this->getCacheId());
-
-    $this->recalculateInfo();
-    $this->recalculateFilenames();
-
+    $this->cache->set($this->getCacheId(), $extensions);
     $this->extensions = $extensions;
     return $this->extensions;
   }
@@ -202,7 +202,7 @@ protected function doListExtensions() {
     $extensions = $this->doScanExtensions($listing);
 
     // Read info files for each extension.
-    foreach ($extensions as $key => $extension) {
+    foreach ($extensions as $name => $extension) {
       // Look for the info file.
       $extension->info = $this->infoParser->parse($extension->getPathname());
 
@@ -211,12 +211,12 @@ protected function doListExtensions() {
       $extension->info['mtime'] = $extension->getMTime();
 
       // Merge in defaults and save.
-      $extensions[$key]->info = $extension->info + $this->defaults;
+      $extensions[$name]->info = $extension->info + $this->defaults;
 
       // Invoke hook_system_info_alter() to give installed modules a chance to
       // modify the data in the .info.yml files if necessary.
       // @todo Remove $type argument, obsolete with $module->getType().
-      $this->moduleHandler->alter('system_info', $extensions[$key]->info, $extensions[$key], $this->type);
+      $this->moduleHandler->alter('system_info', $extensions[$name]->info, $extensions[$name], $this->type);
     }
 
     return $extensions;
@@ -240,7 +240,6 @@ protected function doListExtensions() {
    *   array is returned.
    */
   public function getInfo($name = NULL) {
-    $this->extensionInfo;
     if (!isset($this->extensionInfo)) {
       if ($cache = $this->cache->get("system.{$this->type}.info")) {
         $info = $cache->data;
@@ -258,10 +257,8 @@ public function getInfo($name = NULL) {
 
   protected function recalculateInfo() {
     $info = [];
-    foreach ($this->listExtensions() as $extension_name => $filename) {
-      if (isset($data[$extension_name])) {
-        $info[$extension_name] = $data[$extension_name]->info;
-      }
+    foreach ($this->listExtensions() as $name => $extension) {
+      $info[$name] = $extension->info;
     }
     // Store the module information in cache. This cache is cleared by
     // calling system_rebuild_module_data(), for example, when listing
@@ -279,7 +276,7 @@ protected function recalculateInfo() {
   public function getFilenames() {
     if (!isset($this->fileNames)) {
       $file_names = \Drupal::state()->get("system.{$this->type}.files");
-      if (!isset($files)) {
+      if (!isset($file_names)) {
         $file_names = $this->recalculateFilenames();
       }
       $this->fileNames = $file_names;
@@ -291,8 +288,8 @@ protected function recalculateFilenames() {
     $file_names = [];
     $extensions = $this->listExtensions();
     ksort($extensions);
-    foreach ($extensions as $extension_name => $extension) {
-      $file_names[$extension_name] = $extension->getPathname();
+    foreach ($extensions as $name => $extension) {
+      $file_names[$name] = $extension->getPathname();
     }
     \Drupal::state()->set("system.{$this->type}.files", $file_names);
     return $file_names;
diff --git a/core/lib/Drupal/Core/Extension/ModuleExtensionList.php b/core/lib/Drupal/Core/Extension/ModuleExtensionList.php
index 3561b28..9e7763e 100644
--- a/core/lib/Drupal/Core/Extension/ModuleExtensionList.php
+++ b/core/lib/Drupal/Core/Extension/ModuleExtensionList.php
@@ -129,7 +129,6 @@ protected function doListExtensions() {
       $module->weight = isset($installed_modules[$name]) ? $installed_modules[$name] : 0;
       $module->status = (int) isset($installed_modules[$name]);
       $module->schema_version = SCHEMA_UNINSTALLED;
-      $files[$name] = $module->getPathname();
     }
     $extensions = $this->moduleHandler->buildModuleDependencies($extensions);