Can't download attachments with russian letters in name (from issue) in Redmine 3.4.0 with Rails 4.2.9, but work corect with Rails 4.2.8

[VVD]

Steps to reproduce

1. Install Redmine 3.4.0.
2. Update Rails to 4.2.9.
3. Add issue in installed Redmine.
4. Attach file with russian letters in name to this issue.
5. Try do download this file.

Expected behavior

Browser start downloading file.

Actual behavior

Error 404.

System configuration

Rails version: 4.2.9

Ruby version: 2.4.1

But it work fine with Rails 4.2.8 in same environment.

More information is here: https://www.redmine.org/issues/26337#note-9

With Rails 4.2.9 production.log:

Started GET "/attachments/5450/%d0%a2%d0%97.pdf" for 10.0.0.1 at 2017-07-04 08:12:53 +0300
Processing by AttachmentsController#show as HTML
  Parameters: {"id"=>"5450", "filename"=>"\xD0\xA2\xD0\x97.pdf"}
  Current user: VVD (id=3)
  Rendered common/error.html.erb within layouts/base (0.2ms)
Filter chain halted as :find_attachment rendered or redirected
Completed 404 Not Found in 76ms (Views: 28.6ms | ActiveRecord: 42.5ms)

With Rails 4.2.8 production.log:

Started GET "/attachments/5450/%d0%a2%d0%97.pdf" for 10.0.0.1 at 2017-07-04 11:06:56 +0300
Processing by AttachmentsController#show as HTML
  Parameters: {"id"=>"5450", "filename"=>"ТЗ.pdf"}
  Current user: VVD (id=3)
  Rendered common/_other.html.erb (0.8ms)
  Rendered layouts/_file.html.erb (17.1ms)
  Rendered attachments/other.html.erb within layouts/base (26.4ms)
Completed 200 OK in 123ms (Views: 76.3ms | ActiveRecord: 21.1ms)

Look at difference:

"filename"=>"\xD0\xA2\xD0\x97.pdf"
"filename"=>"ТЗ.pdf"

[VVD]

I made workaround (dirty hack):

--- rails-4.2.9.orig/actionpack/lib/action_dispatch/journey/router/utils.rb
+++ rails-4.2.9/actionpack/lib/action_dispatch/journey/router/utils.rb
@@ -13,13 +13,13 @@
         #   normalize_path("")      # => "/"
         #   normalize_path("/%ab")  # => "/%AB"
         def self.normalize_path(path)
-          encoding = path.encoding
+          encoding = Encoding::UTF_8
           path = "/#{path}"
           path.squeeze!('/')
           path.sub!(%r{/+\Z}, '')
           path.gsub!(/(%[a-f0-9]{2})/) { $1.upcase }
           path = "/" if path == "".freeze
           path.force_encoding(encoding)
           path
         end