Fix pipeline status for commit caching

Fixes a bug with the commit cache key used for partial
caching, where the key was changing on every page load.

Changelog: fixed

app/helpers/commits_helper.rb

@@ -161,7 +161,7 @@ module CommitsHelper
       ref,
       {
         merge_request: merge_request,
-        pipeline_status: hashed_pipeline_status(commit, ref),
+        pipeline_status: commit.status_for(ref),
         xhr: request.xhr?,
         controller: controller.controller_path,
         path: @path # referred to in #link_to_browse_code
@@ -242,14 +242,4 @@ module CommitsHelper
       project_commit_path(project, commit)
     end
   end
-
-  private
-
-  def hashed_pipeline_status(commit, ref)
-    status = commit.status_for(ref)
-
-    return if status.nil?
-
-    Digest::SHA1.hexdigest(status.to_s)
-  end
 end

lib/gitlab/ci/status/core.rb

@@ -11,6 +11,8 @@ module Gitlab
 
         attr_reader :subject, :user
 
+        delegate :cache_key, to: :subject
+
         def initialize(subject, user)
           @subject = subject
           @user = user

spec/helpers/commits_helper_spec.rb

@@ -294,7 +294,8 @@ RSpec.describe CommitsHelper do
     subject { helper.commit_partial_cache_key(commit, ref: ref, merge_request: merge_request, request: request) }
 
     let(:commit) { create(:commit).present(current_user: user) }
-    let(:commit_status) { create(:commit_status) }
+    let(:commit_status) { Gitlab::Ci::Status::Running.new(pipeline, user) }
+    let(:pipeline) { create(:ci_pipeline, :running) }
     let(:user) { create(:user) }
     let(:ref) { "master" }
     let(:merge_request) { nil }
@@ -315,7 +316,7 @@ RSpec.describe CommitsHelper do
       is_expected.to include(
         {
           merge_request: merge_request,
-          pipeline_status: Digest::SHA1.hexdigest(commit_status.to_s),
+          pipeline_status: commit_status,
           xhr: true,
           controller: "commits",
           path: current_path