diff --git a/app/models/pull_request.rb b/app/models/pull_request.rb
index 0966ec9e4..a854b8fc0 100644
--- a/app/models/pull_request.rb
+++ b/app/models/pull_request.rb
@@ -164,7 +164,7 @@ class PullRequest < ActiveRecord::Base
   def merge
     clone
     message = "Merge pull request ##{serial_id} from #{from_project_owner_uname}/#{from_project_name}:#{from_ref}\r\n #{title}"
-    %x(cd #{path} && git checkout #{to_ref} && git merge --no-ff #{from_branch} -m #{message.shellescape})
+    %x(cd #{path} && git checkout #{to_ref.shellescape} && git merge --no-ff #{from_branch.shellescape} -m #{message.shellescape})
   end
 
   def clone
@@ -194,8 +194,9 @@ class PullRequest < ActiveRecord::Base
         system 'git', 'reset', '--hard', "origin/#{to_ref}"
       end
       unless tags.include? from_ref
-        system 'git', 'branch', '-D', from_branch
-        system 'git', 'fetch', head, "+#{from_ref}:#{from_branch}"
+        system 'git', 'checkout', from_branch
+        system 'git', 'reset', '--hard', "#{head}/#{from_ref}"
+        system 'git', 'checkout', to_ref
       end
     end
   end
diff --git a/config/environments/development.rb b/config/environments/development.rb
index 98a9d21f5..ed182ee10 100644
--- a/config/environments/development.rb
+++ b/config/environments/development.rb
@@ -1,4 +1,20 @@
 # -*- encoding : utf-8 -*-
+
+class DisableAssetsLogger
+  def initialize(app)
+    @app = app
+    Rails.application.assets.logger = Logger.new('/dev/null')
+  end
+
+  def call(env)
+    previous_level = Rails.logger.level
+    Rails.logger.level = Logger::ERROR if env['PATH_INFO'].index("/assets/") == 0
+    @app.call(env)
+  ensure
+    Rails.logger.level = previous_level
+  end
+end
+
 Rosa::Application.configure do
   # Settings specified here will take precedence over those in config/application.rb
 
@@ -40,4 +56,6 @@ Rosa::Application.configure do
 
   # Log the query plan for queries taking more than this (works with SQLite, MySQL, and PostgreSQL)
   config.active_record.auto_explain_threshold_in_seconds = 0.5
+
+  config.middleware.insert_before Rails::Rack::Logger, DisableAssetsLogger
 end