Merge branch 'master' into adequaterecord

* master: (70 commits)
  [ci skip] Added link to ruby-lang.org installation.
  Use the index on hidden field
  `collection_check_boxes` respects `:index` option for the hidden filed name.
  docs, double meaning of `serialize` argument. Closes #14284.
  Just call read_attribute, no need to use `send`.
  - Fix lingering reference to `:text` instead of the newer `:plain` - Section references `form_tag` instead of the `form_for` used in the example
  again, read_attribute is public, so just call it
  read_attribute is public, so we should just call it
  Disable assest cache store in docs [ci skip]
  Make counter cache decrementation on destroy idempotent
  Write the failing test case for concurrent counter cache
  [ci skip] Use plain underscore instead of "\_".
  Update documentation to use Rails.application instead
  Add a changelog entry for #14546 [ci skip]
  Move tests for deep_dup and duplicable to object directory
  Missing 'are' in note - [ci skip]
  CollectionHelpers now accepts a readonly option
  Fix a few typos [ci skip]
  Bundle tzinfo-data on :x64_mingw (64-bit Ruby on Windows).
  don't bother with an offset if the offset is zero
  ...

1 files changed, 1 insertions, 1 deletions

diff --git a/activesupport/lib/active_support/core_ext/kernel.rb b/activesupport/lib/active_support/core_ext/kernel.rb
index aa19aed43b..293a3b2619 100644
--- a/activesupport/lib/active_support/core_ext/kernel.rb
+++ b/activesupport/lib/active_support/core_ext/kernel.rb
@@ -1,5 +1,5 @@
 require 'active_support/core_ext/kernel/agnostics'
 require 'active_support/core_ext/kernel/concern'
-require 'active_support/core_ext/kernel/debugger'
+require 'active_support/core_ext/kernel/debugger' if RUBY_VERSION < '2.0.0'
 require 'active_support/core_ext/kernel/reporting'
 require 'active_support/core_ext/kernel/singleton_class'