Keep comments on the top of Drupal config export files

YAML patch

diff --git a/core/lib/Drupal/Core/Config/FileStorage.php b/core/lib/Drupal/Core/Config/FileStorage.php
index fe202a3e0e..b0c27a32bb 100644
--- a/core/lib/Drupal/Core/Config/FileStorage.php
+++ b/core/lib/Drupal/Core/Config/FileStorage.php
@@ -147,7 +147,8 @@ public function write($name, array $data) {
     }
 
     $target = $this->getFilePath($name);
-    $status = @file_put_contents($target, $encoded_data);
+    $prefix = @file_get_contents('/tmp/cexprepend' . substr($target, strlen($this->directory)));
+    $status = @file_put_contents($target, $prefix . $encoded_data);
     if ($status === FALSE) {
       // Try to make sure the directory exists and try writing again.
       $this->ensureStorage();
diff --git a/drush/Commands/pre_config_export/PreConfigExportHook.php b/drush/Commands/pre_config_export/PreConfigExportHook.php
new file mode 100644
index 0000000000..c740b9db6a
--- /dev/null
+++ b/drush/Commands/pre_config_export/PreConfigExportHook.php
@@ -0,0 +1,21 @@
+<?php
+
+namespace Drush\Commands\pre_config_export;
+
+use Drupal\Core\Site\Settings;
+use Drush\Commands\DrushCommands;
+
+/**
+ * Pre config export hook file.
+ */
+class PreConfigExportHook extends DrushCommands {
+
+  /**
+   * @hook pre-command-event config:export
+   */
+  public function onPreConfigExport() {
+    $directory = realpath(Settings::get('config_sync_directory'));
+    system(sprintf('../scripts/pre_config_export.sh "%s"', $directory));
+  }
+
+}
diff --git a/scripts/pre_config_export.sh b/scripts/pre_config_export.sh
new file mode 100755
index 0000000000..c51de1ea11
--- /dev/null
+++ b/scripts/pre_config_export.sh
@@ -0,0 +1,6 @@
+#!/bin/sh
+rm -rf /tmp/cexprepend
+mkdir /tmp/cexprepend
+cd "$1"
+find . -type d -exec mkdir -p /tmp/cexprepend/{} \;
+find . -type f -exec awk 'FNR==1 { close(out); out = "/tmp/cexprepend/" FILENAME; } /^#/ { print >out }' {} +

The idea is to grab the comments from the current config export using the awk script from https://stackoverflow.com/a/79034808/308851 and then put those back during config export. (This works with busybox, doesn't require any GNU tools.)