This is already handled by #find, it's a duplicate check, since
find_with_ids is not called from anywhere else.

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.

    User.order("name asc").order("created_at desc")
    # SELECT * FROM users ORDER BY created_at desc, name asc

This also affects order defined in `default_scope` or any kind of associations.

It has been moved to active_record_deprecated_finders.

Use #to_a instead.

`FinderMethods#exists?` finder method now returns *false* with the *false* argument

reflection.

ActiveRecord::FinderMethods#construct_limited_ids_condition will raise
ThrowResult if the limited reflection comes back empty. The other callers
of #construct_limited_ids_condition handle this exception (more specifically,
the callers of construct_relation_for*), but #exists? didn't until now.

This behavior was added in be4ecdcc.

Closes #1139.

Fixes #2553, #1141, #1623 and #2062.

Minimal change to query generation of exists? that makes SQLServer and others happy that do not work without a column alias.
Conflicts:
	activerecord/lib/active_record/relation/finder_methods.rb

This reverts commit fa6d921e.

Reason: Not a fan of such massive changes. We usually close such changes
if made to Rails master as a pull request. Following the same principle
here and reverting.

[ci skip]

For future reference, this is the regex I used: ^\s*#\s*\n(?!\s*#). Replace
with the first match, and voilà! Note that the regex matches a little bit too
much, so you probably want to `git add -i .` and go through every single diff
to check if it actually should be changed.

default order clause (fixes #5103)

"Predicates in Rails rely on standard Ruby semantics for boolean values
and guarantee no singletons whatsoever." - @fxn

This reverts commit 5cad7a0d, reversing
changes made to bb842e8d.