Actually, private methods cannot be called with `self.`, so it's not just redundant, it's a bad habit in Ruby

And let's see if it still fails...

this fixes sqlite3-1.3.12/lib/sqlite3/pragmas.rb:301: warning: method redefined; discarding old integrity_check

Optimizing information_schema query for `foreign_keys`

Need `table_name` to avoid all databases scan.
See https://dev.mysql.com/doc/refman/5.7/en/information-schema-optimization.html.

```
> EXPLAIN SELECT fk.referenced_table_name AS 'to_table', fk.referenced_column_name AS 'primary_key', fk.column_name AS 'column', fk.constraint_name AS 'name', rc.update_rule AS 'on_update', rc.delete_rule AS 'on_delete' FROM information_schema.key_column_usage fk JOIN information_schema.referential_constraints rc USING (constraint_schema, constraint_name) WHERE fk.referenced_column_name IS NOT NULL AND fk.table_schema = 'activerecord_unittest' AND fk.table_name = 'fk_test_has_pk' AND rc.table_name = 'fk_test_has_pk'\G
*************************** 1. row ***************************
           id: 1
  select_type: SIMPLE
        table: fk
   partitions: NULL
         type: ALL
possible_keys: NULL
          key: TABLE_SCHEMA,TABLE_NAME
      key_len: NULL
          ref: NULL
         rows: NULL
     filtered: NULL
        Extra: Using where; Open_full_table; Scanned 0 databases
*************************** 2. row ***************************
           id: 1
  select_type: SIMPLE
        table: rc
   partitions: NULL
         type: ALL
possible_keys: NULL
          key: TABLE_NAME
      key_len: NULL
          ref: NULL
         rows: NULL
     filtered: NULL
        Extra: Using where; Open_full_table; Scanned 1 database; Using join buffer (Block Nested Loop)
2 rows in set, 1 warning (0.00 sec)
```

Fixes #27579.

We use aes-256-cbc cipher by default and it only accepts keys with 32
bytes at max.

Closes #27576.

[ci skip]

Clarify that mattr_* creates public methods

Add "check_parameters" option to "current_page?"

Fix typo in asset_pipeline.md [ci skip]

Require "models/post" before "models/comment"

Refer a similar pull request #26370

Update asset fingerprinting information

Warn when has_many through is defined before through association

https://github.com/rails/rails/issues/26834

This change raises an error if a has_many through association
is defined before the through association.

Fix default locale code example [ci skip]

Rails env for empty string env vars

Example:

For "http://www.example.com/shop/checkout?order=desc&page=1"

current_page?('http://www.example.com/shop/checkout')
=> true

current_page?(
  'http://www.example.com/shop/checkout',
  check_parameters: true
)
=> false

Fix `find_by` and `where` consistency

The alternative of #26213.

Currently `find_by` and `where` with AR object return inconsistent
result. This is caused by statement cache does not support AR object.
Passing to finder method to fix the issue.

Fixes #26210.

Revert "Merge pull request #21233 from mtsmfm/disable-referential-integrity-without-superuser-privileges"

This reverts commit eeac6151, reversing
changes made to 5c40239d.

Reason: Broke the isolated tests.
https://travis-ci.org/rails/rails/builds/188721346

This reverts commit 1e969bfb, reversing
changes made to a5041f26.

Reason: It breaks the public API

Fix generator command for nested (namespaced) rails engine

Remove unnecessary require statements

`Metal#env` --> `ActionController::Metal#env`

[ci skip]

Fix typo s/permited/permitted/