Refactor Satellite#clear and rename it to clear_and_update!

lib/gitlab/satellite/action.rb

@@ -50,10 +50,7 @@ module Gitlab
       #
       # Note: use this within #in_locked_and_timed_satellite
       def prepare_satellite!(repo)
-        project.satellite.clear
-
-        repo.git.reset(hard: true)
-        repo.git.fetch({}, :origin)
+        project.satellite.clear_and_update!
         repo.git.config({}, "user.name", user.name)
         repo.git.config({}, "user.email", user.email)

lib/gitlab/satellite/satellite.rb

@@ -9,20 +9,10 @@ module Gitlab
         @project = project
       end
-      #will be deleted all branches except PARKING_BRANCH
-      def clear
-        Dir.chdir(path) do
-          heads = Grit::Repo.new(".").heads.map{|head| head.name}
-          if heads.include? PARKING_BRANCH
-            `git checkout #{PARKING_BRANCH}`
-          else
-            `git checkout -b #{PARKING_BRANCH}`
-          end
-          heads.delete(PARKING_BRANCH)
-          heads.each do |head|
-            `git branch -D #{head}`
-          end
-        end
+      def clear_and_update!
+        delete_heads!
+        clear_working_dir!
+        update_from_source!
       end
       def create
@@ -36,6 +26,44 @@ module Gitlab
       def path
         Rails.root.join("tmp", "repo_satellites", project.path)
       end
+
+      private
+
+      # Clear the working directory
+      def clear_working_dir!
+        repo.git.reset(hard: true)
+      end
+
+      # Deletes all branches except the parking branch
+      #
+      # This ensures we have no name clashes or issues updating branches when
+      # working with the satellite.
+      def delete_heads!
+        heads = repo.heads.map{|head| head.name}
+
+        # update or create the parking branch
+        if heads.include? PARKING_BRANCH
+          repo.git.checkout({}, PARKING_BRANCH)
+        else
+          repo.git.checkout({b: true}, PARKING_BRANCH)
+        end
+
+        # remove the parking branch from the list of heads ...
+        heads.delete(PARKING_BRANCH)
+        # ... and delete all others
+        heads.each { |head| repo.git.branch({D: true}, head) }
+      end
+
+      def repo
+        @repo ||= Grit::Repo.new(path)
+      end
+
+      # Updates the satellite from Gitolite
+      #
+      # Note: this will only update remote branches (i.e. origin/*)
+      def update_from_source!
+        repo.git.fetch({}, :origin)
+      end
     end
   end
 end