Merge pull request #9581 from ruby/atomic-write-vendored-compact-index

Write vendored compact_index files atomically

(cherry picked from commit 86b63d5)

Author: hsbt

bundler/spec/support/rubygems_ext.rb

@@ -99,7 +99,9 @@ def install_vendored_compact_index
           url = "https://raw.githubusercontent.com/rubygems/rubygems.org/#{ref}/#{path}"
           target = target_root.join(path)
           FileUtils.mkdir_p(File.dirname(target))
-          File.write(target, URI.parse(url).open(&:read))
+          tmp = "#{target}.tmp"
+          File.write(tmp, URI.parse(url).open(&:read))
+          File.rename(tmp, target)
         end
       end
     end