Merge branch 'fix-lfs-ci-fetch' into 'master'

Fix LFS CI fetch

## What does this MR do?
Fixes LFS fetching for CI objects that were kind of broken.

## Why was this MR needed?
This also refactors LFS tests to be a blackbox tests instead of whitebox tests. Actually testing GrackAuth instead of LFSRouter.

## Related isssues
Resolves: https://gitlab.com/gitlab-org/gitlab-ci-multi-runner/issues/1199

- [ ] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [ ] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [ ] API support added
- Tests
  - [ ] Added for this feature/bug
  - [ ] All builds are passing
- [ ] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [ ] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [ ] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)


See merge request !5270

CHANGELOG

@@ -31,6 +31,7 @@ v 8.10.0 (unreleased)
   - Support U2F devices in Firefox. !5177
   - Fix issue, preventing users w/o push access to sort tags !5105 (redetection)
   - Add Spring EmojiOne updates.
+  - Fix fetching LFS objects for private CI projects
   - Add syntax for multiline blockquote using `>>>` fence !3954
   - Fix viewing notification settings when a project is pending deletion
   - Updated compare dropdown menus to use GL dropdown

lib/gitlab/backend/grack_auth.rb

@@ -63,7 +63,7 @@ module Grack
     def ci_request?(login, password)
       matched_login = /(?<s>^[a-zA-Z]*-ci)-token$/.match(login)
 
-      if project && matched_login.present? && git_cmd == 'git-upload-pack'
+      if project && matched_login.present?
         underscored_service = matched_login['s'].underscore
 
         if underscored_service == 'gitlab_ci'

lib/gitlab/lfs/response.rb

@@ -47,6 +47,8 @@ module Gitlab
       end
 
       def render_storage_upload_store_response(oid, size, tmp_file_name)
+        return render_forbidden unless tmp_file_name
+
         render_response_to_push do
           render_lfs_upload_ok(oid, size, tmp_file_name)
         end

lib/gitlab/lfs/router.rb

@@ -74,8 +74,6 @@ module Gitlab
           lfs.render_storage_upload_authorize_response(oid, size)
         else
           tmp_file_name = sanitize_tmp_filename(@request.env['HTTP_X_GITLAB_LFS_TMP'])
-          return nil unless tmp_file_name
-
           lfs.render_storage_upload_store_response(oid, size, tmp_file_name)
         end
       end