Partially revert 14b20ce

The failure have returned, so disabling the tests again. (The upgrade is
fine to keep.)

activesupport/test/file_evented_update_checker_test.rb

@@ -5,6 +5,11 @@ require 'file_update_checker_shared_tests'
 class FileEventedUpdateCheckerTest < ActiveSupport::TestCase
   include FileUpdateCheckerSharedTests
 
+  def setup
+    skip if ENV['LISTEN'] == '0'
+    super
+  end
+
   def new_checker(files = [], dirs = {}, &block)
     ActiveSupport::FileEventedUpdateChecker.new(files, dirs, &block).tap do
       wait

ci/travis.rb

@@ -111,8 +111,14 @@ class Build
   end
 
   def env
-    # Provide extra ENV variables for the build here
-    {}
+    if activesupport? && !isolated?
+      # There is a known issue with the listen tests that casuses files to be
+      # incorrectly GC'ed even when they are still in-use. The current is to
+      # only run them in isolation to avoid randomly failing our test suite.
+      { 'LISTEN' => '0' }
+    else
+      {}
+    end
   end
 
   def run_bug_report_templates