Addresses regression with jenkins setup that does not use the multiproject setup

app/models/project_services/jenkins_service.rb

@@ -14,6 +14,7 @@
 
 class JenkinsService < CiService
   prop_accessor :project_url
+  prop_accessor :multiproject_enabled
 
   validates :project_url, presence: true, if: :activated?
 
@@ -46,13 +47,23 @@ class JenkinsService < CiService
 
   def fields
     [
-      { type: 'text', name: 'project_url', placeholder: 'Jenkins project URL like http://jenkins.example.com/job/my-project/' }
+      { type: 'text', name: 'project_url', placeholder: 'Jenkins project URL like http://jenkins.example.com/job/my-project/' },
+      { type: 'checkbox', name: 'multiproject_enabled', title: "Multi-project setup enabled?",
+        help: "Multi-project mode is configured in Jenkins Gitlab Hook plugin." }
     ]
   end
 
+  def multiproject_enabled?
+    self.multiproject_enabled == '1'
+  end
+
   def build_page(sha, ref = nil)
+    if multiproject_enabled?
       base_url = ref.nil? || ref == 'master' ? project_url : "#{project_url}_#{ref}"
       base_url + "/scm/bySHA1/#{sha}"
+    else
+      project_url + "/scm/bySHA1/#{sha}"
+    end
   end
 
   def commit_status(sha, ref = nil)

spec/models/project_services/jenkins_service_spec.rb

@@ -35,16 +35,17 @@ describe JenkinsService do
 eos
     end
 
+    describe :commit_status do
       before do
         @service = JenkinsService.new
         allow(@service).to receive_messages(
           service_hook: true,
           project_url: 'http://jenkins.gitlab.org/projects/2',
+          multiproject_enabled: '1',
           token: 'verySecret'
         )
       end
 
-    describe :commit_status do
       statuses = { 'blue.png' => 'success', 'yellow.png' => 'failed', 'red.png' => 'failed', 'aborted.png' => 'failed', 'blue-anime.gif' => 'running', 'grey.png' => 'pending' }
       statuses.each do |icon, state|
         it "should have a status of #{state} when the icon #{icon} exists." do
@@ -54,6 +55,17 @@ eos
       end
     end
 
+    describe 'multiproject enabled' do
+      before do
+        @service = JenkinsService.new
+        allow(@service).to receive_messages(
+          service_hook: true,
+          project_url: 'http://jenkins.gitlab.org/projects/2',
+          multiproject_enabled: '1',
+          token: 'verySecret'
+        )
+      end
+
       describe :build_page do
         it { expect(@service.build_page("2ab7834c", 'master')).to eq("http://jenkins.gitlab.org/projects/2/scm/bySHA1/2ab7834c") }
       end
@@ -62,4 +74,25 @@ eos
         it { expect(@service.build_page("2ab7834c", 'test_branch')).to eq("http://jenkins.gitlab.org/projects/2_test_branch/scm/bySHA1/2ab7834c") }
       end
     end
+
+    describe 'multiproject disabled' do
+      before do
+        @service = JenkinsService.new
+        allow(@service).to receive_messages(
+          service_hook: true,
+          project_url: 'http://jenkins.gitlab.org/projects/2',
+          multiproject_enabled: '0',
+          token: 'verySecret'
+        )
+      end
+
+      describe :build_page do
+        it { expect(@service.build_page("2ab7834c", 'master')).to eq("http://jenkins.gitlab.org/projects/2/scm/bySHA1/2ab7834c") }
+      end
+
+      describe :build_page_with_branch do
+        it { expect(@service.build_page("2ab7834c", 'test_branch')).to eq("http://jenkins.gitlab.org/projects/2/scm/bySHA1/2ab7834c") }
+      end
+    end
+  end
 end