Do not raise an error when trying to persist a job

app/models/commit_status.rb

@@ -51,8 +51,8 @@ class CommitStatus < ActiveRecord::Base
   # We still create some CommitStatuses outside of CreatePipelineService.
   #
   # These are pages deployments and external statuses. We now handle these
-  # using CreateJobService, but we still need to ensure that a job has a
-  # stage assigned. TODO, In future releases we will add model validation.
+  # jobs using CreateJobService, but we still need to ensure that a job has
+  # a stage assigned. TODO, In future releases we will add model validation.
   #
   before_create unless: :importing? do
     Ci::EnsureStageService.new(project, user).execute(self) do |stage|

app/services/ci/create_job_service.rb

@@ -5,7 +5,7 @@ module Ci
         Ci::EnsureStageService.new(project, current_user)
           .execute(subject)
-        subject.save!
+        subject.save
       end
     end
   end

lib/api/commit_statuses.rb

@@ -96,7 +96,7 @@ module API
         if status.new_record?
           Ci::CreateJobService.new(@project, current_user).execute(status)
         else
-          status.save!
+          status.save if status.changed?
         end
         render_validation_error!(status) if status.invalid?

spec/services/ci/create_job_service_spec.rb

@@ -17,4 +17,10 @@ describe Ci::CreateJobService, '#execute' do
   it 'ensures that a job has a stage assigned' do
     expect(service.execute(status).stage_id).to be_present
   end
+
+  it 'does not raise error if status is invalid' do
+    status.name = nil
+
+    expect(service.execute(status)).not_to be_persisted
+  end
 end