The following test is failing intermittently at quite a high rate:

HostJSTest::create new host page.test_0003_saves correct values for inherited fields without hostgroup (from HostJSTest__create new host page)
Took 35 sec.

Timeout::Error: execution expired
    test/integration/host_js_test.rb:166:in `block (3 levels) in <class:HostJSTest>'
    test/integration/host_js_test.rb:165:in `block (2 levels) in <class:HostJSTest>' (Timeout::Error)
/usr/local/rvm/gems/ruby-2.0.0-p353@test_develop-3/gems/poltergeist-1.10.0/lib/capybara/poltergeist/web_socket_server.rb:79

It looks similar to #15134 where network interfaces are being filled in and there's no waiting for the various AJAX calls on the interface modal.