Merge remote-tracking branch 'upstream/master' into pipeline-emailspipeline-emails

* upstream/master: (58 commits)
  Update endpoint to username validator
  change border color to variable
  Add todo for deprecated user routes and more information about deprecation to changelog
  Provide better error message to the user
  Apply better hierarchy to markdown headers and issue/mr titles
  Swapped button text manipulation outcomes for the toggle query
  Fixed find file keyboard navigation
  Update CHANGELOG for 8.12.7
  Added download-button class and applied button margin
  Enable activerecord_sane_schema_dumper for test
  Updated logo from @luke
  Fix broken specs on MySQL after https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/6896
  Fix Test Env (proper error handling when gitlab-shell is not clonned)
  Fix randomly crashing spinach test for merge request
  [Great spinach fix] Replace gsub with delete
  Remove carriage returns from commit description as summary is on a newline and will always include carriage returns
  Convert due_date_select.js filetype to es6.
  Stop directly parsing due_date with Date.parse, prefer parsing implicitly.
  Improve spec for pipeline metrics worker
  Add Pipeline metrics worker
  ...

2 files changed, 21 insertions, 6 deletions

diff --git a/app/controllers/application_controller.rb b/app/controllers/application_controller.rb
index 705824502eb..37600ed875c 100644
--- a/app/controllers/application_controller.rb
+++ b/app/controllers/application_controller.rb
@@ -118,7 +118,12 @@ class ApplicationController < ActionController::Base
   end
 
   def render_404
-    render file: Rails.root.join("public", "404"), layout: false, status: "404"
+    respond_to do |format|
+      format.html do
+        render file: Rails.root.join("public", "404"), layout: false, status: "404"
+      end
+      format.any { head :not_found }
+    end
   end
 
   def no_cache_headers
diff --git a/app/controllers/projects/merge_requests_controller.rb b/app/controllers/projects/merge_requests_controller.rb
index 9207c954335..a39b47b6d95 100644
--- a/app/controllers/projects/merge_requests_controller.rb
+++ b/app/controllers/projects/merge_requests_controller.rb
@@ -9,15 +9,15 @@ class Projects::MergeRequestsController < Projects::ApplicationController
 
   before_action :module_enabled
   before_action :merge_request, only: [
-    :edit, :update, :show, :diffs, :commits, :conflicts, :builds, :pipelines, :merge, :merge_check,
+    :edit, :update, :show, :diffs, :commits, :conflicts, :conflict_for_path, :builds, :pipelines, :merge, :merge_check,
     :ci_status, :ci_environments_status, :toggle_subscription, :cancel_merge_when_build_succeeds, :remove_wip, :resolve_conflicts, :assign_related_issues
   ]
   before_action :validates_merge_request, only: [:show, :diffs, :commits, :builds, :pipelines]
-  before_action :define_show_vars, only: [:show, :diffs, :commits, :conflicts, :builds, :pipelines]
+  before_action :define_show_vars, only: [:show, :diffs, :commits, :conflicts, :conflict_for_path, :builds, :pipelines]
   before_action :define_widget_vars, only: [:merge, :cancel_merge_when_build_succeeds, :merge_check]
   before_action :define_commit_vars, only: [:diffs]
   before_action :define_diff_comment_vars, only: [:diffs]
-  before_action :ensure_ref_fetched, only: [:show, :diffs, :commits, :builds, :conflicts, :pipelines]
+  before_action :ensure_ref_fetched, only: [:show, :diffs, :commits, :builds, :conflicts, :conflict_for_path, :pipelines]
   before_action :close_merge_request_without_source_project, only: [:show, :diffs, :commits, :builds, :pipelines]
   before_action :apply_diff_view_cookie!, only: [:new_diffs]
   before_action :build_merge_request, only: [:new, :new_diffs]
@@ -33,7 +33,7 @@ class Projects::MergeRequestsController < Projects::ApplicationController
 
   before_action :authenticate_user!, only: [:assign_related_issues]
 
-  before_action :authorize_can_resolve_conflicts!, only: [:conflicts, :resolve_conflicts]
+  before_action :authorize_can_resolve_conflicts!, only: [:conflicts, :conflict_for_path, :resolve_conflicts]
 
   def index
     @merge_requests = merge_requests_collection
@@ -170,6 +170,16 @@ class Projects::MergeRequestsController < Projects::ApplicationController
     end
   end
 
+  def conflict_for_path
+    return render_404 unless @merge_request.conflicts_can_be_resolved_in_ui?
+
+    file = @merge_request.conflicts.file_for_path(params[:old_path], params[:new_path])
+
+    return render_404 unless file
+
+    render json: file, full_content: true
+  end
+
   def resolve_conflicts
     return render_404 unless @merge_request.conflicts_can_be_resolved_in_ui?
 
@@ -184,7 +194,7 @@ class Projects::MergeRequestsController < Projects::ApplicationController
       flash[:notice] = 'All merge conflicts were resolved. The merge request can now be merged.'
 
       render json: { redirect_to: namespace_project_merge_request_url(@project.namespace, @project, @merge_request, resolved_conflicts: true) }
-    rescue Gitlab::Conflict::File::MissingResolution => e
+    rescue Gitlab::Conflict::ResolutionError => e
       render status: :bad_request, json: { message: e.message }
     end
   end