From ec6d727af8a670b9c98cacb3bc17a9b5dbfec91d Mon Sep 17 00:00:00 2001
From: Jordi Boggiano <j.boggiano@seld.be>
Date: Wed, 15 Apr 2015 02:48:10 +0100
Subject: [PATCH] Add comment about --, refs #3853

---
 src/Composer/Downloader/GitDownloader.php | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/Composer/Downloader/GitDownloader.php b/src/Composer/Downloader/GitDownloader.php
index 12e5a2a5d..70c9ae435 100644
--- a/src/Composer/Downloader/GitDownloader.php
+++ b/src/Composer/Downloader/GitDownloader.php
@@ -215,6 +215,11 @@ class GitDownloader extends VcsDownloader
      */
     protected function updateToCommit($path, $reference, $branch, $date)
     {
+        // This uses the "--" sequence to separate branch from file parameters.
+        //
+        // Otherwise git tries the branch name as well as file name.
+        // If the non-existent branch is actually the name of a file, the file
+        // is checked out.
         $template = 'git checkout %s -- && git reset --hard %1$s';
         $branch = preg_replace('{(?:^dev-|(?:\.x)?-dev$)}i', '', $branch);