Replace files atomically when relocating, take two

Library/Homebrew/keg_fix_install_names.rb

@@ -38,16 +38,14 @@ class Keg
       end
     end
 
-    (pkgconfig_files | libtool_files | script_files).each do |file|
-      file.ensure_writable do
-        file.open('rb') do |f|
-          s = f.read
-          s.gsub!(old_cellar, new_cellar)
-          s.gsub!(old_prefix, new_prefix)
-          f.reopen(file, 'wb')
-          f.write(s)
-        end
-      end
+    files = pkgconfig_files | libtool_files | script_files
+
+    files.group_by { |f| f.stat.ino }.each_value do |first, *rest|
+      s = first.open("rb", &:read)
+      s.gsub!(old_cellar, new_cellar)
+      s.gsub!(old_prefix, new_prefix)
+      first.atomic_write(s)
+      rest.each { |file| FileUtils.ln(first, file, :force => true) }
     end
   end