These are no longer used since 66736c8e.

Change :github git source for bug report templates

Because the reflection doesn't have `foreign_type` unless the
association is a polymorphic association.

:github source uses `git://` url by default, `https://` is recommended.
See http://bundler.io/v1.15/guides/git.html#security

We do the same in our `Gemfile` and templates.

Add a space to RefineryCMS in Engine guide [ci skip]

I do not want to set the expectation that any enumerable object should
behave this way, but this case in particular comes up frequently enough
that I'm caving on this one.

Fixes #30684.

PERF: Partially recover some performance when preloading. 

Fix typo in 'find_in_batches' example

Fixed broken `bundle exec rake install`

Benchmark Script:
```
require 'active_record'
require 'benchmark/ips'

ActiveRecord::Base.establish_connection(ENV.fetch('DATABASE_URL'))
ActiveRecord::Migration.verbose = false

ActiveRecord::Schema.define do
  create_table :users, force: true do |t|
    t.string :name, :email
    t.integer :topic_id
    t.timestamps null: false
  end

  create_table :topics, force: true do |t|
    t.string :title
    t.timestamps null: false
  end
end

attributes = {
  name: 'Lorem ipsum dolor sit amet, consectetur adipiscing elit.',
  email: 'foobar@email.com'
}

class Topic < ActiveRecord::Base
  has_many :users
end

class User < ActiveRecord::Base
  belongs_to :topic
end

100.times do
  User.create!(attributes)
end

users = User.first(50)

Topic.create!(title: 'This is a topic', users: users)

Benchmark.ips do |x|
  x.config(time: 10, warmup: 5)

  x.report("preload") do
    User.includes(:topic).all.to_a
  end
end
```

Before:
```
Calculating -------------------------------------
             preload    40.000  i/100ms
-------------------------------------------------
             preload    407.962  (± 1.5%) i/s -      4.080k
```

After:
```
alculating -------------------------------------
             preload    43.000  i/100ms
-------------------------------------------------
             preload    427.567  (± 1.6%) i/s -      4.300k
```

Remove unused fixtures

`about_yml_plugins` is no longer used since 82b9b151

* According to the official website, it seems that "RefineryCMS" is "Refinery CMS".
* See at: http://www.refinerycms.com/

Preload digest/sha2 to avoid thread safe error.

Respect quiet option in all process of `rails new` command

Fix minor CodeClimate issue

Based on, yet closes https://github.com/rails/rails/pull/30708

Fix the session test by properly truncating the legacy encryption
key for cbc encryption. Borrowed straight from 👆.

Fix the cookies test a little differently than the PR. Basically
keep every config within the config block.

[ Michael Coyne & Kasper Timm Hansen ]

I got this error in production using Puma in multi-threaded mode:

```
RuntimeError: Digest::Base cannot be directly inherited in Ruby
from active_support/security_utils.rb:23:in `variable_size_secure_compare'
from active_support/security_utils.rb:23:in `hexdigest'
from active_support/security_utils.rb:23:in `digest'
```

Looks like Digest uses const_missing to load Digest::SHA256 (https://github.com/ruby/ruby/blob/trunk/ext/digest/lib/digest.rb#L8)

- https://bugs.ruby-lang.org/issues/9494
- https://github.com/ruby/ruby/commit/c02fa39463a0c6bf698b01bc610135604aca2ff4

New missing backquotes [ci skip]

PERF: Restore memoization when preloading associations.

Benchmark Script

```
require 'active_record'
require 'benchmark/ips'
require 'ruby-prof'
require 'memory_profiler'
require 'byebug'

ActiveRecord::Base.establish_connection(ENV.fetch('DATABASE_URL'))
ActiveRecord::Migration.verbose = false

ActiveRecord::Schema.define do
  create_table :users, force: true do |t|
    t.string :name, :email
    t.integer :topic_id
    t.timestamps null: false
  end

  create_table :topics, force: true do |t|
    t.string :title
    t.timestamps null: false
  end
end

attributes = {
  name: 'Lorem ipsum dolor sit amet, consectetur adipiscing elit.',
  email: 'foobar@email.com'
}

class Topic < ActiveRecord::Base
  has_many :users
end

class User < ActiveRecord::Base
  belongs_to :topic
end

100.times do
  User.create!(attributes)
end

users = User.first(50)

Topic.create!(title: 'This is a topic', users: users)

Benchmark.ips do |x|
  x.config(time: 10, warmup: 5)

  x.report("preload") do
    User.includes(:topic).all.to_a
  end
end
```

Before

```
Calculating -------------------------------------
             preload    26.000  i/100ms
-------------------------------------------------
             preload    265.347  (± 3.0%) i/s -      2.652k
```

After

```
Calculating -------------------------------------
             preload    39.000  i/100ms
-------------------------------------------------
             preload    406.053  (± 1.7%) i/s -      4.095k
```

If specify the `quiet` option, expect that no status will be shown.
However, some process show status. This suppresses all status output.

It's done inside each test via assert_called_with or Kernel.expects

Update Form Helpers guide [ci skip]

Remove unused variable `gem_version` from `tasks/release.rb`

https://travis-ci.org/rails/rails/jobs/279300966#L2600

The result of `Loofah::HTML5::Scrub.scrub_css` was changed since
v2.1.0.rc1.

https://github.com/flavorjones/loofah/commit/ca56295ff9e802018ea18d23ed49be235a95ccad

Refactor Css::Generators::ScaffoldGenerator

It's become clear to me that the use case is still a bit muddy
and the upgrade path is going to be tough for people to figure
out.

This attempts at understanding it better through documentation,
but still needs follow up work.

[ Michael Coyne & Kasper Timm Hansen ]