`Kernel.#spawn` execute command via the shell if contains shell
metacharacters in the command.
In that case, return value of `spawn` is pid of the shell, not the server.
Therefore, just killing the pid will leave the process of server.

In order to correctly kill the server, send a signal to the process
group, not the process.

`through_reflection` and `source_reflection` are used only in the class.

Use released `redis-namespace` instead of master version

The `redis-namespace` 1.6.0 includes redis-rb 4.0 support.

Fix output of `select_tag` with `include_blank: true` [ci skip]

Merge pull request #31084 from y-yagi/do_not_run_active_storage_install_when_bundle_install_is_skipped

Do not run active storage install when bundle install is skipped

Since #24923, if use `select_tag` with `include_blank: true`, an empty
label is added.

Since isolation application is generated with the `--skip-gemfile`
option, so `active_storage:install` is not executed.

In order to execute the `rails` command, need to run bundle install in
advance.
Therefore, if skipped bundle install, `rails` command may fail and
should not do it.

Fix comment in `check_class_collision` [ci skip]

`ScaffoldBase` was changed to `ResourceHelpers` by 0efedf2a.

Prevent extra string allocations when no 'rel' arg passed

Add cases to test combining validation conditions

Fix `bin/rails db:migrate` with specified `VERSION`

Closes #31073.

`associated_records_by_owner` had returned customizing result before
calling `associate_records_to_owner` for through association subclasses.
Since #22115, `associate_records_to_owner` is called in the method and
not returned owner and result pairs. Removing the method will reduce
method call and block call nesting.

Execute `ConfirmationValidator` validation when `_confirmation`'s value is `false`

 - Test condition that is defined by array of conditions
 - Test condition that is defined by combining :if and :unless
 - Test local condition that is defined by :if
 - Test local condition that is defined by :unless

See http://edgeguides.rubyonrails.org/active_record_validations.html#combining-validation-conditions

Ensure that `bin/rails db:migrate` with specified `VERSION` reverts
all migrations only if `VERSION` is `0`.
Raise error if target migration doesn't exist.

Provide initialization of Active Storage

Make `assert_recognizes` to traverse mounted engines

Handle Timeout.timeout in rails queries

Refactored preloading of a though assocations

Omit `rails activestorage:install` for jdbcmysql, jdbc and shebang tests

AppGeneratorTest#test_config_jdbcmysql_database

  rails aborted!
  LoadError: Could not load 'active_record/connection_adapters/mysql_adapter'.
  Make sure that the adapter in config/database.yml is valid.
  If you use an adapter other than 'mysql2', 'postgresql' or 'sqlite3' add
  the necessary adapter gem to the Gemfile.
  (compressed)
  bin/rails:4:in `<main>'
  Tasks: TOP => activestorage:install => environment
  (See full trace by running task with --trace)

AppGeneratorTest#test_config_jdbc_database

  rails aborted!
  LoadError: Could not load 'active_record/connection_adapters/jdbc_adapter'.
  Make sure that the adapter in config/database.yml is valid.
  If you use an adapter other than 'mysql2', 'postgresql' or 'sqlite3' add
  the necessary adapter gem to the Gemfile.
  (compressed)
  bin/rails:4:in `<main>'
  Tasks: TOP => activestorage:install => environment
  (See full trace by running task with --trace)

AppGeneratorTest#test_shebang_is_added_to_rails_file

  /home/ubuntu/.rbenv/versions/2.4.1/bin/ruby: no Ruby script found in input (LoadError)

Prevent PendingMigrationError in tests

 * Run `bin/rails db:migrate RAILS_ENV=test` in test_cases before start tests to prevent PendingMigrationError
 * FileUtils.rm_r("db/migrate")
 * --skip-active-storage

Fix failed tests in `railties/test/railties/engine_test.rb`

Related to #30111

Imporve `SharedGeneratorTests#test_default_frameworks_are_required_when_others_are_removed`

 - Explicitly skip active_storage
 - Ensure that skipped frameworks are commented
 - Ensure that default frameworks are not commented

Fix error `Errno::ENOSPC: No space left on device - sendfile`

Since `rails new` runs `rails active_storage:install`
that boots an app.

Since adding Bootsnap 0312a5c6
during booting an app, it creates the cache:

   264K    tmp/cache/bootsnap-load-path-cache
   27M     tmp/cache/bootsnap-compile-cache

* teardown_app must remove app

Closes #30102

Revert part 787fe90d

--skip-active-storage pass throughs `rails plugin new`

Add changelog entry about default initialization of Active Storage

```
[NoMethodError]: undefined method `state' for nil:NilClass  Method:[rescue in block in refresh]
```

In `within_new_transaction`, there is the possibility that
`begin_transaction` returns a `nil`. (i.e.: so `transaction = nil`)
So this method is checking `transaction` for nil in 2 spots.

Unfortunately, there is one line that is not checking `transaction` for `nil`
That line, `commit_transaction`, throws an exception for us in AR 5.0.0.1

The problem with the method is finally realized in the error checking itself.
it calls `transaction.state` (i.e.: nil.state) and that is the final exception
raised.

The actual underlying (user) issue is hidden by this line.

Solution is test transaction for nil.

Resolve Minitest 6 deprecation in assert_no_changes

These changes resolve a deprecation warning in `assert_no_changes`
when asserting that an expression evaluates to `nil` before and after
the passed block is evaluated.

The smallest demonstration of this edge case:

```ruby
assert_no_changes "nil" do
  true # noop
end
```

Under the covers, this is evaluating

```ruby
assert_equal nil, nil
```

Minitest 5 issues a deprecation warning, and Minitest will fail
completely.

For additional context, the motivations and implications of this change
to Minitest have been discussed at length in [seattlerb/minitest#666][].

[seattlerb/minitest#666]: https://github.com/seattlerb/minitest/issues/666

Acronym inflections are stored with lowercase keys in the hash but
the match wasn't being lowercased before being looked up in the hash.
This shouldn't have any performance impact because before it would
fail to find the acronym and perform the `downcase` operation anyway.

Fixes #31052.

Fix french spelling mistake

Mirror the API of Ruby stdlib for #prev_day, #next_day, #prev_month, #next_month, #prev_year, #next_year

Trés -> Très 
https://fr.wiktionary.org/wiki/tr%C3%A8s