diff -u b/core/modules/system/system.module b/core/modules/system/system.module
--- b/core/modules/system/system.module
+++ b/core/modules/system/system.module
@@ -870,6 +870,10 @@
             $info[$module] = $data[$module]->info;
           }
         }
+        // Store the module info in cache. We rely on consecutive calls to
+        // system_rebuild_module_data() to reset this key, such as when
+        // listing modules, (un)installating modules, importing configuration,
+        // updating the site and when flushing all caches.
         \Drupal::cache()->set('system.module.info', $info);
       }
       return $info;
@@ -1011,16 +1015,12 @@
       $files[$name] = $module->getPathname();
     }
     $modules = \Drupal::moduleHandler()->buildModuleDependencies($modules);
-    // Store the module info in cache. We rely on consecutive calls to
-    // system_rebuild_module_data() to reset this key, such as when
-    // listing modules, (un)installating modules, importing configuration,
-    // updating the site and when flushing all caches.
     $modules_cache = $modules;
 
     // Store filenames to allow drupal_get_filename() to
     // retrieve them without having to rebuild or scan the filesystem.
     \Drupal::state()->set('system.module.files', $files);
-    // Clear module info cache.
+    // Clear the module info cache.
     \Drupal::cache()->delete('system.module.info');
     drupal_static_reset('system_get_info:module');
   }