Merge branch 'pmq20/gitlab-ce-psvr/change-head' into 'master'

Use rugged to change HEAD

_Originally opened at !2850 by @pmq20._

Needless to invoke gitlab_shell here, which is slow.

See merge request !3705

CHANGELOG

@@ -42,6 +42,7 @@ v 8.7.0 (unreleased)
   - Add default scope to projects to exclude projects pending deletion
   - Allow to close merge requests which source projects(forks) are deleted.
   - Ensure empty recipients are rejected in BuildsEmailService
+  - Use rugged to change HEAD in Project#change_head (P.S.V.R)
   - API: Ability to filter milestones by state `active` and `closed` (Robert Schilling)
   - API: Fix milestone filtering by `iid` (Robert Schilling)
   - API: Delete notes of issues, snippets, and merge requests (Robert Schilling)

app/models/project.rb

@@ -865,7 +865,9 @@ class Project < ActiveRecord::Base
 
   def change_head(branch)
     repository.before_change_head
-    gitlab_shell.update_repository_head(self.path_with_namespace, branch)
+    repository.rugged.references.create('HEAD',
+                                        "refs/heads/#{branch}",
+                                        force: true)
     reload_default_branch
   end
 

lib/gitlab/backend/shell.rb

@@ -54,19 +54,6 @@ module Gitlab
                                    "#{path}.git", "#{new_path}.git"])
     end
 
-    # Update HEAD for repository
-    #
-    # path - project path with namespace
-    # branch - repository branch name
-    #
-    # Ex.
-    #  update_repository_head("gitlab/gitlab-ci", "3-1-stable")
-    #
-    def update_repository_head(path, branch)
-      Gitlab::Utils.system_silent([gitlab_shell_projects_path, 'update-head',
-                                   "#{path}.git", branch])
-    end
-
     # Fork repository to new namespace
     #
     # path - project path with namespace