…assignment assigns to existing record if the association is not yet loaded

Issue rails#2: Nested Attributes assignment does not affect the record in the association target when callback triggers loading of the association

Complete rewrite of tests

Fix an issue with where clause with a dot character.

Backport Patches for CVE-2013-0333

Clean up JobWrappers::ResqueWrapper.perform

All the methods that invoke `text_field_tag` (such as `hidden_field_tag`)
and all the methods that invoke `number_field_tag` (that is `range_field_tag`)
do not need to call `stringify_keys` on their `options` parameter since the
`text_field_tag` method [is already doing it internally](https://github.com/claudiob/rails/blob/4159134524f4c78d008eef9d9a17f73a3172dcc8/actionview/lib/action_view/helpers/form_tag_helper.rb#L182):

```ruby
def text_field_tag(name, value = nil, options = {})
  tag :input, { "type" => "text", "name" => name, "id" => sanitize_to_id(name), "value" => value }.update(options.stringify_keys)
end
```

and `number_field_tag` is [already doing it internally](https://github.com/claudiob/rails/blob/e3207bdbba55f3806441f22b175557579bc0b051/actionview/lib/action_view/helpers/form_tag_helper.rb#L780) as well:

```ruby
def number_field_tag(name, value = nil, options = {})
  options = options.stringify_keys
  ...
end

[Note #1: My code uses `merge` to respect the existing behavior of
duplicating the `options` hash before updating its keys, see #17096 (comment)]

[Note #2: My code uses symbols instead of strings (e.g.: `:hidden`) to look
forward to future version of Ruby/Raiks (GC symbols); the result of the method,
however, is the same, because the symbols are stringified inside `text_field_tag`]

[Note #3: I had previously created a similar PR #17096 but decided to
split it into multiple PRs given the feedback received in the comments]

Remove guides/output directory from git

Fix n+1 query problem when eager loading nil associations (fixes #18312)

Fix repo infomation in welcome messages

This is an instance method on the request object now so we don't need it
anymore

And make sure that it doesn't even try to call the method in the target.