[ci skip] tag for skipping builds

app/controllers/projects_controller.rb

@@ -63,7 +63,7 @@ class ProjectsController < ApplicationController
     @build = @project.register_build(ref: params[:ref])
     if @build and @build.id
-      Runner.perform_async(@build.id)
+      Runner.perform_async(@build.id) unless @build.ci_skip?
       redirect_to project_build_path(@project, @build)
     else
       redirect_to project_path(@project), notice: 'Branch is not defined for this project'

app/models/build.rb

@@ -55,6 +55,10 @@ class Build < ActiveRecord::Base
     project.gitlab?
   end
+  def ci_skip?
+    !!(commit.message =~ /(\[ci skip\])/)
+  end
+
   def git_author_name
     commit.author.name
   rescue

spec/models/build_spec.rb

@@ -15,6 +15,18 @@ describe Build do
   it { should respond_to :git_author_name }
   it { should respond_to :short_sha }
   it { should respond_to :trace_html }
+
+  describe "#ci_skip?" do
+    let(:project) { FactoryGirl.create(:project) }
+    let(:build) { project.register_build(ref: 'master') }
+    it 'true if commit message contains [ci skip]' do
+      build.commit.stub(:message) { 'Small typo [ci skip]' }
+      build.ci_skip?.should == true
+    end
+    it 'false if commit message does not contain [ci skip]' do
+      build.ci_skip?.should == false
+    end
+  end
 end