From 28861ac92d910abbe014a05c4418ee077371d9ca Mon Sep 17 00:00:00 2001
From: Xu Cheng <xucheng@me.com>
Date: Thu, 14 Jul 2016 13:14:49 +0800
Subject: [PATCH] CurlDownloadStrategy#_fetch: fix unintended variable
 modification

---
 Library/Homebrew/download_strategy.rb | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Library/Homebrew/download_strategy.rb b/Library/Homebrew/download_strategy.rb
index 4fa0b3803e..061e551a68 100644
--- a/Library/Homebrew/download_strategy.rb
+++ b/Library/Homebrew/download_strategy.rb
@@ -333,7 +333,7 @@ class CurlDownloadStrategy < AbstractFileDownloadStrategy
     url = @url
 
     if ENV["HOMEBREW_ARTIFACT_DOMAIN"]
-      url.sub!(%r{^((ht|f)tps?://)?}, ENV["HOMEBREW_ARTIFACT_DOMAIN"].chomp("/") + "/")
+      url = url.sub(%r{^((ht|f)tps?://)?}, ENV["HOMEBREW_ARTIFACT_DOMAIN"].chomp("/") + "/")
       ohai "Downloading from #{url}"
     end