From 071108b868387d9a6d5033c3d7a2dab4ee1e3996 Mon Sep 17 00:00:00 2001
From: Markus Reiter <me@reitermark.us>
Date: Mon, 1 Oct 2018 10:40:36 +0200
Subject: [PATCH] Fix `atomic_write` inside non-sticky directory.

---
 Library/Homebrew/extend/pathname.rb | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/Library/Homebrew/extend/pathname.rb b/Library/Homebrew/extend/pathname.rb
index 57629775d8..02ff1e35b4 100644
--- a/Library/Homebrew/extend/pathname.rb
+++ b/Library/Homebrew/extend/pathname.rb
@@ -160,9 +160,16 @@ class Pathname
     open("a", *open_args) { |f| f.puts(content) }
   end
 
-  # NOTE always overwrites
+  # NOTE: This always overwrites.
   def atomic_write(content)
+    # The enclosing `mktmpdir` and the `chmod` are a workaround
+    # for https://github.com/rails/rails/pull/34037.
     Dir.mktmpdir(".d", dirname) do |tmpdir|
+      begin
+        FileUtils.chmod "+t", dirname
+      rescue Errno::EPERM
+        :ignore
+      end
       File.atomic_write(self, tmpdir) do |file|
         file.write(content)
       end