Don't try to create diffs if one of the branch is missing

Also fix a few tests

app/models/merge_request.rb

@@ -443,7 +443,8 @@ class MergeRequest < ActiveRecord::Base
   end
 
   def reload_diff_if_branch_changed
-    if source_branch_changed? || target_branch_changed?
+    if (source_branch_changed? || target_branch_changed?) &&
+        (source_branch_head && target_branch_head)
       reload_diff
     end
   end

spec/controllers/projects/issues_controller_spec.rb

@@ -841,7 +841,7 @@ describe Projects::IssuesController do
   describe 'POST #toggle_award_emoji' do
     before do
       sign_in(user)
-      project.team << [user, :developer]
+      project.add_developer(user)
     end
 
     it "toggles the award emoji" do

spec/features/merge_requests/filter_by_labels_spec.rb

 require 'rails_helper'
 
-feature 'Merge Request filtering by Labels', js: true do
+feature 'Merge Request filtering by Labels', :js do
   include FilteredSearchHelpers
   include MergeRequestHelpers
 
@@ -12,9 +12,9 @@ feature 'Merge Request filtering by Labels', js: true do
   let!(:feature) { create(:label, project: project, title: 'feature') }
   let!(:enhancement) { create(:label, project: project, title: 'enhancement') }
 
-  let!(:mr1) { create(:merge_request, title: "Bugfix1", source_project: project, target_project: project, source_branch: "bugfix1") }
-  let!(:mr2) { create(:merge_request, title: "Bugfix2", source_project: project, target_project: project, source_branch: "bugfix2") }
-  let!(:mr3) { create(:merge_request, title: "Feature1", source_project: project, target_project: project, source_branch: "feature1") }
+  let!(:mr1) { create(:merge_request, title: "Bugfix1", source_project: project, target_project: project, source_branch: "fix") }
+  let!(:mr2) { create(:merge_request, title: "Bugfix2", source_project: project, target_project: project, source_branch: "wip") }
+  let!(:mr3) { create(:merge_request, title: "Feature1", source_project: project, target_project: project, source_branch: "improve/awesome") }
 
   before do
     mr1.labels << bug
@@ -25,7 +25,7 @@ feature 'Merge Request filtering by Labels', js: true do
     mr3.title = "Feature1"
     mr3.labels << feature
 
-    project.team << [user, :master]
+    project.add_master(user)
     sign_in(user)
 
     visit project_merge_requests_path(project)

spec/features/merge_requests/user_lists_merge_requests_spec.rb

@@ -24,12 +24,10 @@ describe 'Projects > Merge requests > User lists merge requests' do
            milestone: create(:milestone, due_date: '2013-12-12'),
            created_at: 2.minutes.ago,
            updated_at: 2.minutes.ago)
-    # lfs in itself is not a great choice for the title if one wants to match the whole body content later on
-    # just think about the scenario when faker generates 'Chester Runolfsson' as the user's name
     create(:merge_request,
-           title: 'merge_lfs',
+           title: 'merge-test',
            source_project: project,
-           source_branch: 'merge_lfs',
+           source_branch: 'merge-test',
            created_at: 3.minutes.ago,
            updated_at: 10.seconds.ago)
   end
@@ -38,7 +36,7 @@ describe 'Projects > Merge requests > User lists merge requests' do
     visit_merge_requests(project, assignee_id: IssuableFinder::NONE)
 
     expect(current_path).to eq(project_merge_requests_path(project))
-    expect(page).to have_content 'merge_lfs'
+    expect(page).to have_content 'merge-test'
     expect(page).not_to have_content 'fix'
     expect(page).not_to have_content 'markdown'
     expect(count_merge_requests).to eq(1)
@@ -47,7 +45,7 @@ describe 'Projects > Merge requests > User lists merge requests' do
   it 'filters on a specific assignee' do
     visit_merge_requests(project, assignee_id: user.id)
 
-    expect(page).not_to have_content 'merge_lfs'
+    expect(page).not_to have_content 'merge-test'
     expect(page).to have_content 'fix'
     expect(page).to have_content 'markdown'
     expect(count_merge_requests).to eq(2)
@@ -57,14 +55,14 @@ describe 'Projects > Merge requests > User lists merge requests' do
     visit_merge_requests(project, sort: sort_value_recently_created)
 
     expect(first_merge_request).to include('fix')
-    expect(last_merge_request).to include('merge_lfs')
+    expect(last_merge_request).to include('merge-test')
     expect(count_merge_requests).to eq(3)
   end
 
   it 'sorts by oldest' do
     visit_merge_requests(project, sort: sort_value_oldest_created)
 
-    expect(first_merge_request).to include('merge_lfs')
+    expect(first_merge_request).to include('merge-test')
     expect(last_merge_request).to include('fix')
     expect(count_merge_requests).to eq(3)
   end
@@ -72,7 +70,7 @@ describe 'Projects > Merge requests > User lists merge requests' do
   it 'sorts by last updated' do
     visit_merge_requests(project, sort: sort_value_recently_updated)
 
-    expect(first_merge_request).to include('merge_lfs')
+    expect(first_merge_request).to include('merge-test')
     expect(count_merge_requests).to eq(3)
   end
 

spec/finders/environments_finder_spec.rb

@@ -12,7 +12,7 @@ describe EnvironmentsFinder do
 
     context 'tagged deployment' do
       before do
-        create(:deployment, environment: environment, ref: '1.0', tag: true, sha: project.commit.id)
+        create(:deployment, environment: environment, ref: 'v1.1.0', tag: true, sha: project.commit.id)
       end
 
       it 'returns environment when with_tags is set' do

spec/lib/gitlab/git/repository_spec.rb

@@ -1196,9 +1196,8 @@ describe Gitlab::Git::Repository, seed_helper: true do
 
   def create_remote_branch(repository, remote_name, branch_name, source_branch_name)
     source_branch = repository.branches.find { |branch| branch.name == source_branch_name }
-    repository.write_ref(
-      "refs/remotes/#{remote_name}/#{branch_name}",
-      source_branch.dereferenced_target.sha)
+    rugged = repository.rugged
+    rugged.references.create("refs/remotes/#{remote_name}/#{branch_name}", source_branch.dereferenced_target.sha)
   end
 
   # Build the options hash that's passed to Rugged::Commit#create