Fix insertion of records for hmt association with scope, fix #3548
Auto-generate stable fixture UUIDs on PostgreSQL.
Fixes: #11524
Merge pull request #12016 from roderickvd/uuid_fixes

Auto-generate stable fixture UUIDs on PostgreSQL

Conflicts:
	activerecord/CHANGELOG.md
	activerecord/lib/active_record/fixtures.rb
	activerecord/test/cases/adapters/postgresql/uuid_test.rb
	activesupport/CHANGELOG.md
Keep debugger support only for rubies < 2.0.0
Update Gemfile templates to provide correct debugger
Update debugging guide to use byebug
Add a failing test for a URL helper that was broken by a6b9ea2.
Isolate debugger related code
Prevent generation of extra whitespace in templates
Fix error for aggregate methods with select, see issue #13648
Merge branch 'master' into rm-uuid-fixtures

Conflicts:
	activerecord/CHANGELOG.md
	activesupport/CHANGELOG.md
No need to call send
Merge branch 'rm-uuid-fixtures'
Remove warning of unused variable
Add after_commit/after_rollback to callback list

Adding after_commit/after_rollback to list of callbacks in order helps
explain the callback order as well as making it consistent with the API
docs at http://api.rubyonrails.org/classes/ActiveRecord/Callbacks.html
[ci skip] Remove false documentation
Merge pull request #14695 from akshay-vishnoi/doc_changes

[ci skip] Remove false documentation
Merge pull request #14694 from heironimus/callback_guide

Add after_commit/after_rollback to callback list
Merge pull request #12829 from iantropov/issue_insert_via_hmt_scope_3548

Fix insertion of records for hmt association with scope

Conflicts:
	activerecord/CHANGELOG.md
docs, make association `autosave: true` examples runnable. Closes #14700

[ci skip]

The examples are written in a way you expect them to be executable.
However one snippet assumed there to be two comments when only one
was created above.

The defined models did not extend `ActiveRecord::Base`

The example used `comments.last.mark_for_destruction`. This does no
longer load the whole collection but just the last record. It is
then refetcht on subsequent calls to `last`. This breaks the example.