Merge branch 'fix-invalid-symbolic-ref' into 'master'

Ignore symbolic refs that point to deleted branches

While trying to test another bug, I deleted a branch that happened to have a symbolic ref pointing to it. I wasn't able to even reach the GitLab dashboard as a result. The error that showed up:

```
Rugged::ReferenceError - Reference 'refs/heads/new-branch' not found:
  gitlab_git (7.2.6) lib/gitlab_git/repository.rb:56:in `block in branches'
  gitlab_git (7.2.6) lib/gitlab_git/repository.rb:55:in `branches'
  gitlab_git (7.2.6) lib/gitlab_git/repository.rb:50:in `branch_names'
  gitlab_git (7.2.6) lib/gitlab_git/repository.rb:116:in `discover_default_branch'
  gitlab_git (7.2.6) lib/gitlab_git/repository.rb:33:in `initialize'
  app/models/repository.rb:11:in `initialize'
  app/models/project.rb:263:in `repository'
  app/models/project.rb:426:in `avatar_in_git'
  app/models/project.rb:435:in `avatar_url'
  app/helpers/application_helper.rb:41:in `project_icon'
  app/views/shared/_project.html.haml:5:in `block (2 levels) in _app_views_shared__project_html_haml__222087319794829046_70255909387840'
  haml (4.0.5) lib/haml/helpers.rb:368:in `block in capture_haml'
  haml (4.0.5) lib/haml/helpers.rb:608:in `with_haml_buffer'
  haml (4.0.5) lib/haml/helpers.rb:364:in `capture_haml'
  haml (4.0.5) lib/haml/helpers/xss_mods.rb:61:in `capture_haml_with_haml_xss'
  haml (4.0.5) lib/haml/helpers/action_view_mods.rb:45:in `capture_with_haml'
```

The repository had this state:

```
$ git branch -a
* master
  test
  test-symlink -> new-branch
```

See merge request !33

Author: Douwe Maan

CHANGELOG

@@ -1,3 +1,6 @@
+v 7.2.8
+  - Ignore symbolic refs that point to deleted branches (Stan Hu)
+
 v 7.2.7
   - Order result of `Repository#commits_between` by date.
   - Include branch/tag name in archive file and dirname

Gemfile

@@ -6,6 +6,7 @@ group :development do
   gem 'rubocop'
   gem 'coveralls', require: false
   gem 'rspec'
+  gem 'rspec-mocks'
   gem 'webmock'
   gem 'guard'
   gem 'guard-rspec'

Gemfile.lock

@@ -116,6 +116,10 @@ DEPENDENCIES
   pry
   rake
   rspec
+  rspec-mocks
   rubocop
   simplecov
   webmock
+
+BUNDLED WITH
+   1.10.5

lib/gitlab_git/repository.rb

@@ -53,8 +53,12 @@ def branch_names
       # Returns an Array of Branches
       def branches
         rugged.branches.map do |rugged_ref|
-          Branch.new(rugged_ref.name, rugged_ref.target)
-        end.sort_by(&:name)
+          begin
+            Branch.new(rugged_ref.name, rugged_ref.target)
+          rescue Rugged::ReferenceError
+            # Omit invalid branch
+          end
+        end.compact.sort_by(&:name)
       end
 
       # Returns an Array of tag names

spec/repository_spec.rb

@@ -637,4 +637,17 @@
       @repo.rugged.config.delete('core.autocrlf')
     end
   end
+
+  describe '#branches with deleted branch' do
+    before(:each) do
+      ref = double()
+      ref.stub(:name) { 'bad-branch' }
+      ref.stub(:target) { raise Rugged::ReferenceError }
+      repository.rugged.stub(:branches) { [ref] }
+    end
+
+    it 'should return empty branches' do
+      expect(repository.branches).to eq([])
+    end
+  end
 end