In Ruby 2.3 or later, `String#+@` is available and `+@` is faster than `dup`.

```ruby
# frozen_string_literal: true

require "bundler/inline"

gemfile(true) do
  source "https://rubygems.org"

  gem "benchmark-ips"
end

Benchmark.ips do |x|
  x.report('+@') { +"" }
  x.report('dup') { "".dup }
  x.compare!
end
```

```
$ ruby -v benchmark.rb
ruby 2.5.1p57 (2018-03-29 revision 63029) [x86_64-linux]
Warming up --------------------------------------
                  +@   282.289k i/100ms
                 dup   187.638k i/100ms
Calculating -------------------------------------
                  +@      6.775M (± 3.6%) i/s -     33.875M in   5.006253s
                 dup      3.320M (± 2.2%) i/s -     16.700M in   5.032125s

Comparison:
                  +@:  6775299.3 i/s
                 dup:  3320400.7 i/s - 2.04x  slower

```

Before this change this test was passing even if we revert #31135. The
reason for that is that `app 'development'` will load the environment in
the test process and it is happening before db_create_and_drop is
called.

This was not asserting that the environment was loaded in the db:create
task itself.

To test it we enhance the db:create task with a block that writes to a
tmp file the value of the config. If the environment is loaded before
that task enhancement runs the content of the file will have "true"
insteand of "false".

Let escape_javascript handle conversion to string

This brings `escape_javascript` in line with the behavior of `json_escape` and
allows other value types to be output without needing explicit casting in the
view template.

Example:

    <%= javascript_tag do %>
      var locale = '<%== j I18n.locale %>'; // locale is a symbol
    <% end %>

[close #33907] Error when using "recyclable" cache keys with a store that does not support it

Replace line items with chapters [ci skip]

Line items are a holdover from when orders were used in the examples
instead of books.

Add missing test case for `redirect_to` when request includes a port.

[ci skip] document collection_caching.rb

- Moving the `supports_cache_versioning?` check to a class method. 
- Shorten the method doc. 
- Expand on the error message.

Fix missing curly brace in documentation

This example was just missing a closing curly brace to complete the closure 😄

Ignore psqlrc files when executing psql commands

If you are using the "in cache versioning" also known as "recyclable cache keys" the cache store must be aware of this scheme, otherwise you will generate cache entries that never invalidate.

This PR adds a check to the initialization process to ensure that if recyclable cache keys are being used via 

```
config.active_record.cache_versioning = true
```

Then the cache store needs to show that it supports this versioning scheme. Cache stores can let Rails know that they support this scheme by adding a method `supports_in_cache_versioning?` and returning true.

Correct spelling in "Contributing to Ruby on Rails" guide [ci skip]

ambigity -> ambiguity

Related to #33891

Make sure `assert_enqueued_with()` & `assert_performed_with()` work reliably with hash arguments

Contributing to Ruby on Rails Guide: standardize git remote names [ci skip].

Since #33875, Rails dropped supporting MySQL 5.1 which does not support
utf8mb4. We no longer need to use legacy utf8 (utf8mb3) conservatively.

The test helpers now treat `{ a: 1, b: 2 }` and `{ b: 2, a: 1 }` as equals

CI against PostgreSQL 10

Make a deep copy of the _default_attributes in column_defaults

Update MySQL server version and character set in Rails Guide [skip ci]

Related to #33853

Fixed to RAILS_MASTER_KEY as a default env key for decrypting.

Fixes mistake left in https://github.com/rails/rails/pull/33521/files#diff-2a29095afcfe2c683b82a779a94c2208R59
and misunderstanding in https://github.com/rails/rails/commit/d69b04de0ff33237209afea6f6cac3ab27934908

Make `ActiveRecord::Result#to_a` as alias to `ActiveRecord::Result#to_ary`

`ActiveRecord::Result#to_a` was introduced in #33912.

I would prefer to make `to_a` as alias to the `to_ary` because:
  - It would be clear for users from https://edgeapi.rubyonrails.org/classes/ActiveRecord/Result.html
    that `to_a` and `to_ary` are the same
  - For us it would take less efforts in case if we needed to change the docs
    or implementation, since the methods are the same

Follow up #33912

Don't update counter cache unless the record is actually saved

When column_defaults is called it calls `value` on each instance of
Attribute inside the _default_attributes set. Since value is memoized in
the Attribute instance and that Attribute instance is shared across all
instances of a model the next call to the default value will be memozied
not running the proc defined by the user.

Fixes #33031.

Deprecate ActiveRecord::Result#to_hash in favor of #to_a

When using environment specific credentials, `RAILS_MASTER_KEY` is not used.

Add CSP nonce to `style-src` directive

For `production` environment look first for `config/credentials/production.yml.enc` file that can be decrypted by
`ENV["RAILS_MASTER_KEY"]` or `config/credentials/production.key` master key.
Edit given environment credentials file by command `rails credentials:edit --environment production`.
Default behavior can be overwritten by setting `config.credentials.content_path` and `config.credentials.key_path`.

When you pass an empty array to find we know we shoudl return an empty
array but it is surprising that we are returning the original empty
array instead of a new one.