Allow mounting same engine under several locations

Now that the parameters configurations are only loaded when
ActionController::Base is we need to foce them to load in our tests. In
an application this is not needed since every request already load the
controllers.

Add missing `attr_name.to_s` in `AttributeMutationTracker`

We need to configure it only when ActionController::Base is loaded
otherwise configs on initializers will not work.

Closes #29527.

Allow the use of Bundler 2.0

Fix the class name --> ActionController::Parameters [ci skip]

Fallback Parameters#to_s to Hash#to_s

Fix to scoping is correctly restored

Fix `ids_reader` to respect case sensitive primary key

ActiveRecord: do not create "has many through" records that have been removed

Fix missing formats in route-set URLs

Fix typo in callback deprecation message

Add more explicit guidance on how to fix callback deprecations

Calling `follow_redirect!` does not reset the `html_document`:

Fix regression with date helper in 5.1.2 

ActiveJob::Core#serialize stores provider_job_id (fixes #26581).

* Internally all input is converted to time so that it can be treated
  uniformly.

Remove now-unneeded condition

* Now that all input is treated is converted to time, we no longer need
  to type check it.

Rename variables to clarify their purpose

Extract private method to normalize distance_of_time args to time

Update actionview changelog

Ensure that using correct alias tracker

Rails 5.1.2.rc1 regression - Clear offset cache on CollectionProxy reset/reload

Rails 5.1.2.rc1 regression - Clear offset cache on CollectionProxy reset/reload

Pass `structure_dump_flags` / `structure_load_flags` options before any other:

Removed reference to unexisting methods:

Don't wrap parameters if key already exists

Fix actionpack CHANGELOG.md for v5.1.2 release [ci skip]

This feature will be included in Rails 5.2 and this entry is not needed
yet.

This must have gotten left over on a bad backport. Removed.

This must have gotten left over on a bad backport. Removed.

Fix current_page? helper issue with engine root path

Use of ParameterFilter no longer forces `request.filtered_parameters' class to be Hash

Fix `Relation#exists?` queries with query cache

Remove debug print

Use nullable `id` column instead of a primary key

Fixes FIXME: rb-inotify 0.99 has been released