Scopes can only ever be *not* reflection objects when they are passed in
to the Reflection constructor.  Given this fact, we can eliminate is_a
checks and an intermediate array object by just asking the reflection
object for join scopes.

Remove `node` parameter to `join_constraints`

I don't think we actually need this parameter anymore.  Nobody seems to
be using it.

Fix random failure on system test with ajax

Deprecate implicit coercion of `ActiveSupport::Duration`

If application has ajax, browser may begin request after rollback.
`teardown_fixtures` will be called after `super` on `after_teardown`
so we must call `Capybara.reset_sessions!` before `super`

https://github.com/rails/rails/blob/b61a56541aecd7ac685d4f19d943177a3f1b465a/activerecord/lib/active_record/fixtures.rb#L857

Fix typo in Upgrading Ruby on Rails Guide

fixed suspected typo in sample sql query

Includes a script to ease an app's upgrade.

Update secrets to use modern crypto

Use `blank?` instead of `empty?`

In order to avoid `NoMethodError` when it is nil.

Follow up to 82f7dc61

Currently `ActiveSupport::Duration` implicitly converts to a seconds
value when used in a calculation except for the explicit examples of
addition and subtraction where the duration is the receiver, e.g:

    >> 2 * 1.day
    => 172800

This results in lots of confusion especially when using durations
with dates because adding/subtracting a value from a date treats
integers as a day and not a second, e.g:

    >> Date.today
    => Wed, 01 Mar 2017
    >> Date.today + 2 * 1.day
    => Mon, 10 Apr 2490

To fix this we're implementing `coerce` so that we can provide a
deprecation warning with the intent of removing the implicit coercion
in Rails 5.2, e.g:

    >> 2 * 1.day
    DEPRECATION WARNING: Implicit coercion of ActiveSupport::Duration
    to a Numeric is deprecated and will raise a TypeError in Rails 5.2.
    => 172800

In Rails 5.2 it will raise `TypeError`, e.g:

    >> 2 * 1.day
    TypeError: ActiveSupport::Duration can't be coerced into Integer

This is the same behavior as with other types in Ruby, e.g:

    >> 2 * "foo"
    TypeError: String can't be coerced into Integer
    >> "foo" * 2
    => "foofoo"

As part of this deprecation add `*` and `/` methods to `AS::Duration`
so that calculations that keep the duration as the receiver work
correctly whether the final receiver is a `Date` or `Time`, e.g:

    >> Date.today
    => Wed, 01 Mar 2017
    >> Date.today + 1.day * 2
    => Fri, 03 Mar 2017

Fixes #27457.

Update `DateTime#change` to support usec and nsec

Adding support for these options now allows us to update the
`DateTime#end_of` methods to match the equivalent `Time#end_of`
methods, e.g:

    datetime = DateTime.now.end_of_day
    datetime.nsec == 999999999 # => true

Fixes #21424.

Fixes #28135.

`valid_type?` should accept only supported types

Just dispatch to the command help itself for more info.

Prefer Thor's say method to Kernel's plain puts.

In case there's no $EDITOR assigned users would see a cryptic:

```
% EDITOR= bin/rails secrets:edit
Waiting for secrets file to be saved. Abort with Ctrl-C.
sh: /var/folders/wd/xnncwqp96rj0v1y2nms64mq80000gn/T/secrets.yml.enc: Permission denied
New secrets encrypted and saved.
```

That error is misleading, so give a hint in this easily detectable case.

Fixes #28143.

Use appropriate type for `test_framework` option

Use DEFAULT_CIPHER constant in MessageEncryptor

This fixes the following warning.

```
Expected string default value for '--test-framework'; got false (boolean)
```

Support for using `SELECT` column or expression aliases in the `HAVING`
clause isn't part of the SQL standard so it's better to whitelist the
test for adapters where we know it works and skip it on others.

`HOST` must be all capital letters

Use `inspect` in `type_cast_for_schema` for date/time and decimal values

Ref: https://github.com/rails/rails/blob/master/railties/lib/rails/commands/server/server_command.rb#L194

Allow skipping of turbolinks for test dummy application for plugin/engine

Make required by default test for belongs_to association clearer

`create_join_table` should respect `references` column type

Do not evaluate :if arguments when :on is not satisfied for transaction callbacks

I incorrectly changed behavior of `dup`. Reading the original issue I
thought that `dup` should retain the original contents of the record
and it's associations but it is in fact supposed to be a copy as if a
record had been reinitialized.

This reverts commit ca8c21df.