Build generated .html files broken after upgrading to 3.4.0

middleman version: 3.4.0
ruby version: 2.0.0p247
OS version: OS X 10.11.1

Not sure if this is something on my end but after upgrading middleman to 3.4.0 all of my build generated .html files became empty with absolute path to the layout file in them.

Example:
Contents of test.html file:
/Users/Damir/.../website/source/layouts/homepage.haml

In this example, the homepage.haml file is responsible to provide layout for test.html file.

Building with --verbose switch doesn’t give any warnings, errors or any other useful information. Everything worked before upgrading.

Not sure how relevant this is but this is my Gemfile:

gem "middleman"
gem "middleman-blog"
gem 'middleman-protect-emails'
gem 'middleman-pry'
gem "middleman-syntax"
gem 'middleman-inliner'
gem 'middleman-blog-drafts'
gem 'middleman-deploy'
gem 'middleman-cdn'
gem "redcarpet"
gem 'liquid'
gem 'nokogiri'
gem 'therubyracer'
gem 'less'
gem 'html-proofer'
gem 'builder'
gem 'ansi'

Let me know if I can provide anything else. Thanks!