The method got extracted out from AR::Base in commit
d916c62c, but the tests never did.

The method itself got extracted out from ActiveRecored::Base in commit
ceb33f84, but the test code never did.

The methods got moved to core.rb in commit
b2c9ce34, but the tests never did.

Due to commit 0123c39f, column
topic.unique_replies_count has been added, and these test started to
fail since the tests depends on the topic tables column info.

`AR::Base#to_param` and `AR::Base#cache_key` is defined at
active_record/integration.rb, so tests for those methods should be at
integration_test.rb

Existing code was delegating to the instance with delegate
macro calls, or invoking the instance method to reach
the object and call its instance methods.

But the point is to have a clean class-level interface where
the thread local instance is hidden in the implementation.

References #11c69738.
References #10198.

PerThreadRegistry module.

current_scope and ignore_default_scope locals are brought together under
a registry object.

Introduce test on Error#full_message for attribute with underscores; Fix
some typos

Type a fixo.

These tests should be in inheritance_test.rb since its testing a
feature which is implemented in inheritance.rb

We moved more and more away from passing options to finder / calculation
methods. The `:distinct` option in `#count` was one of the remaining places.
Since we can now combine `Relation#distinct` with `Relation#count` the option
is no longer necessary and can be deprecated.

The similarity of `Relation#uniq` to `Array#uniq` is confusing. Since our
Relation API is close to SQL terms I renamed `#uniq` to `#distinct`.

There is no deprecation. `#uniq` and `#uniq!` are aliases and will continue
to work. I also updated the documentation to promote the use of `#distinct`.

Calling a literal ActiveRecord::Base.new raises NoMethodError,
since it ends up calling Class.abstract_class? which does not exist.
Similarly, instantiating an actual abstract class hits the database,
when conventionally it should immediately throw NotImplementedError.

ActiveRecord::Base can't be made abstract without breaking many,
many things, so check for it separately.

- Extract max timestamp retrieval for cache_key
- Update changelog for cache_key changes

object that has not yet been persisted. This behavior follows the
precedent set by update_columns.

These are duplicated with the tests which are in relations_test.rb

Conflicts:
	activerecord/test/cases/base_test.rb

This can be done using the class attribute cache_timestamp_format

Conflicts:
	railties/guides/source/configuring.textile

Conflicts:
	activerecord/test/models/bulb.rb
	activerecord/test/schema/schema.rb

This reverts commit 3b890520.

Reason: changes made to a test, albeit in commented lines - non-uniform
change.

[ci skip]

In the end I think the pain of implementing this seamlessly was not
worth the gain provided.

The intention was that it would allow plain ruby objects that might not
live in your main application to be subclassed and have persistence
mixed in. But I've decided that the benefit of doing that is not worth
the amount of complexity that the implementation introduced.

Due to its lack of thread safety, we're deprecating this, and it
will be removed in Rails 4.1.

Fixes #4060.