Integration tests are failing to run on Jenkins as the webpack:compile rake task is being called from the integration test helper, but doesn't exist.

+ bundle exec rake pkg:generate_source jenkins:unit jenkins:integration TESTOPTS=-v
rm -rf jenkins/reports/unit/
DEPRECATION WARNING: You are using the a deprecated processor interface #<Proc:0x0000000947bce8@/usr/local/rvm/gems/ruby-2.3.0@test_develop_pr_core-1/gems/autoprefixer-rails-5.2.1.3/lib/autoprefixer-rails/sprockets.rb:25>.
Please update your processor interface:
https://github.com/rails/sprockets/blob/master/guides/extending_sprockets.md#supporting-all-versions-of-sprockets-in-processors
 (called from install at /usr/local/rvm/gems/ruby-2.3.0@test_develop_pr_core-1/gems/autoprefixer-rails-5.2.1.3/lib/autoprefixer-rails/sprockets.rb:25)
The Apipie cache is turned off. Enable it and run apipie:cache rake task to speed up API calls.
DEPRECATION WARNING: You are using the a deprecated processor interface #<Proc:0x0000000a387c28@/usr/local/rvm/gems/ruby-2.3.0@test_develop_pr_core-1/gems/autoprefixer-rails-5.2.1.3/lib/autoprefixer-rails/sprockets.rb:25>.
Please update your processor interface:
https://github.com/rails/sprockets/blob/master/guides/extending_sprockets.md#supporting-all-versions-of-sprockets-in-processors
 (called from install at /usr/local/rvm/gems/ruby-2.3.0@test_develop_pr_core-1/gems/autoprefixer-rails-5.2.1.3/lib/autoprefixer-rails/sprockets.rb:25)
The Apipie cache is turned off. Enable it and run apipie:cache rake task to speed up API calls.
/usr/local/rvm/rubies/ruby-2.3.0/bin/ruby -I"lib:test" -I"/usr/local/rvm/gems/ruby-2.3.0@test_develop_pr_core-1/gems/rake-11.2.2/lib" "/usr/local/rvm/gems/ruby-2.3.0@test_develop_pr_core-1/gems/rake-11.2.2/lib/rake/rake_test_loader.rb" "test/lib/**/*_test.rb" -v --ci-reporter
-- execute("SET CONSTRAINTS ALL DEFERRED;")
   -> 0.0005s
  * DEFERRED: MenuItem::MenuItem#caption should be tested. 
  * DEFERRED: MenuItem::MenuItem#html_options should be tested. 
The Apipie cache is turned off. Enable it and run apipie:cache rake task to speed up API calls.
DEPRECATION WARNING: You are using the a deprecated processor interface #<Proc:0x00000002077bf8@/usr/local/rvm/gems/ruby-2.3.0@test_develop_pr_core-1/gems/autoprefixer-rails-5.2.1.3/lib/autoprefixer-rails/sprockets.rb:25>.
Please update your processor interface:
https://github.com/rails/sprockets/blob/master/guides/extending_sprockets.md#supporting-all-versions-of-sprockets-in-processors
 (called from install at /usr/local/rvm/gems/ruby-2.3.0@test_develop_pr_core-1/gems/autoprefixer-rails-5.2.1.3/lib/autoprefixer-rails/sprockets.rb:25)
/usr/local/rvm/gems/ruby-2.3.0@test_develop_pr_core-1/gems/rake-11.2.2/lib/rake/task_manager.rb:71:in `[]': Don't know how to build task 'webpack:compile' (see --tasks) (RuntimeError)
    from /usr/local/rvm/gems/ruby-2.3.0@test_develop_pr_core-1/gems/rake-11.2.2/lib/rake/task.rb:361:in `[]'
    from /var/lib/workspace/workspace/test_develop_pr_core@2/database/postgresql/label/fast/ruby/2.3/test/integration_test_helper.rb:30:in `<top (required)>'
    from /usr/local/rvm/gems/ruby-2.3.0@test_develop_pr_core-1/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:274:in `require'
    from /usr/local/rvm/gems/ruby-2.3.0@test_develop_pr_core-1/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:274:in `block in require'
    from /usr/local/rvm/gems/ruby-2.3.0@test_develop_pr_core-1/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:240:in `load_dependency'
    from /usr/local/rvm/gems/ruby-2.3.0@test_develop_pr_core-1/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:274:in `require'
    from /var/lib/workspace/workspace/test_develop_pr_core@2/database/postgresql/label/fast/ruby/2.3/test/lib/middleware/catch_json_parse_errors_test.rb:1:in `<top (required)>'
    from /usr/local/rvm/gems/ruby-2.3.0@test_develop_pr_core-1/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:274:in `require'
    from /usr/local/rvm/gems/ruby-2.3.0@test_develop_pr_core-1/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:274:in `block in require'
    from /usr/local/rvm/gems/ruby-2.3.0@test_develop_pr_core-1/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:240:in `load_dependency'
    from /usr/local/rvm/gems/ruby-2.3.0@test_develop_pr_core-1/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:274:in `require'
    from /usr/local/rvm/gems/ruby-2.3.0@test_develop_pr_core-1/gems/rake-11.2.2/lib/rake/rake_test_loader.rb:10:in `block (2 levels) in <main>'
    from /usr/local/rvm/gems/ruby-2.3.0@test_develop_pr_core-1/gems/rake-11.2.2/lib/rake/rake_test_loader.rb:9:in `each'
    from /usr/local/rvm/gems/ruby-2.3.0@test_develop_pr_core-1/gems/rake-11.2.2/lib/rake/rake_test_loader.rb:9:in `block in <main>'
    from /usr/local/rvm/gems/ruby-2.3.0@test_develop_pr_core-1/gems/rake-11.2.2/lib/rake/rake_test_loader.rb:4:in `select'
    from /usr/local/rvm/gems/ruby-2.3.0@test_develop_pr_core-1/gems/rake-11.2.2/lib/rake/rake_test_loader.rb:4:in `<main>'
-- execute("SET CONSTRAINTS ALL DEFERRED;")
   -> 0.0004s
rake aborted!
Command failed with status (1): [ruby -I"lib:test" -I"/usr/local/rvm/gems/ruby-2.3.0@test_develop_pr_core-1/gems/rake-11.2.2/lib" "/usr/local/rvm/gems/ruby-2.3.0@test_develop_pr_core-1/gems/rake-11.2.2/lib/rake/rake_test_loader.rb" "test/lib/**/*_test.rb" -v --ci-reporter]
/usr/local/rvm/gems/ruby-2.3.0@test_develop_pr_core-1/gems/rake-11.2.2/exe/rake:27:in `<top (required)>'
/usr/local/rvm/gems/ruby-2.3.0@test_develop_pr_core-1/bin/ruby_executable_hooks:15:in `eval'
/usr/local/rvm/gems/ruby-2.3.0@test_develop_pr_core-1/bin/ruby_executable_hooks:15:in `<main>'
Tasks: TOP => jenkins:unit => test:lib
(See full trace by running task with --trace)
Run options: -v --ci-reporter --seed 22859

# Running:

ApplicationMailerTest#test_0003_foreman subject prefix is attached = 2.26 s = .
ApplicationMailerTest#test_0004_reply address evalulated at send time = 0.05 s = .
[...]

This is reproducible when running rake jenkins:unit jenkins:integration.