Some tests feature fail when running in random order

[ymph]

When starting the test suite with the --order=random option, some features fail. exemple:

bundle exec cucumber --verbose --order=random

Running the failing features independently is ok each time.

This has been observed in all supported ruby version (2.4.0, 2.3.1, 2.2.4).

Typical output example:

  Scenario: Preserve default image_tag behaviour after build if no resize_to param was given                         # features/generate_image_thumbnails_relative_assets.feature:8
    Given a fixture app "basic-app-relative-assets"                                                                  # middleman-core-4.2.1/lib/middleman-core/step_definitions/middleman_steps.rb:16
    And a successfully built app at "basic-app-relative-assets"                                                      # middleman-core-4.2.1/lib/middleman-core/step_definitions/builder_steps.rb:18
      expected "<path>/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/middleman-cli-4.2.1/bin/middleman:41:in `c....1/bin/middleman:23:in `load'\n\tfrom <path>/.rbenv/versions/2.3.1/bin/middleman:23:in `<main>'" to string includes: "Project built successfully."
      Diff:
      @@ -1,2 +1,5 @@
      -Project built successfully.
      +<path>/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/middleman-cli-4.2.1/bin/middleman:41:in `chdir': No such file or directory @ dir_chdir - <path>/dev/tmp/middleman/middleman-simple-thumbnailer/tmp/aruba/basic-app (Errno::ENOENT)
      +	from <path>/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/middleman-cli-4.2.1/bin/middleman:41:in `<top (required)>'
      +	from <path>/.rbenv/versions/2.3.1/bin/middleman:23:in `load'
      +	from <path>/.rbenv/versions/2.3.1/bin/middleman:23:in `<main>'
       (RSpec::Expectations::ExpectationNotMetError)
      features/generate_image_thumbnails_relative_assets.feature:10:in `And a successfully built app at "basic-app-relative-assets"'