Port GitLab EE ProjectsFinder changes

These changes were added in GitLab EE commit
d39de0ea. The tests were a bit bugged
(they used a non existing group, thus not testing a crucial part) which
I only noticed when porting CE changes to EE.

app/finders/projects_finder.rb

@@ -23,17 +23,17 @@ class ProjectsFinder
     group = options[:group]
     if group
-      base, extra = group_projects(current_user, group)
+      segments = group_projects(current_user, group)
     else
-      base, extra = all_projects(current_user)
+      segments = all_projects(current_user)
     end
-    if base and extra
-      union = Gitlab::SQL::Union.new([base.select(:id), extra.select(:id)])
+    if segments.length > 1
+      union = Gitlab::SQL::Union.new(segments.map { |s| s.select(:id) })
       Project.where("projects.id IN (#{union.to_sql})")
     else
-      base
+      segments.first
     end
   end

spec/finders/projects_finder_spec.rb

@@ -3,10 +3,19 @@ require 'spec_helper'
 describe ProjectsFinder do
   describe '#execute' do
     let(:user) { create(:user) }
-    let!(:private_project)  { create(:project, :private) }
-    let!(:internal_project) { create(:project, :internal) }
-    let!(:public_project)   { create(:project, :public) }
+    let(:group) { create(:group) }
+    let!(:private_project) do
+      create(:project, :private, name: 'A', path: 'A')
+    end
+
+    let!(:internal_project) do
+      create(:project, :internal, group: group, name: 'B', path: 'B')
+    end
+
+    let!(:public_project) do
+      create(:project, :public, group: group, name: 'C', path: 'C')
+    end
     let(:finder) { described_class.new }
@@ -38,8 +47,6 @@ describe ProjectsFinder do
     end
     describe 'with a group' do
-      let(:group) { public_project.group }
-
       describe 'without a user' do
         subject { finder.execute(nil, group: group) }