Fix that #pluck wasn't rescuing ThrowResult, meaning it would blow up when failing to construct_limited_ids_condition.
Add coverage for the fact that pluck without an argument returns all the table's columns.
No point in memoizing a simple literal string.
Make NullRelation a bit more like a real relation by returning 0 for #calculate(:count)
Rather than raising ThrowResult when construct_limited_ids_conditions comes up empty, set the relation to NullRelation and rely on its results.

This will help avoid errors like 2fcafee250ee2, because in most cases NullRelation will do the right thing. Minor bonus is avoiding the use of exceptions for flow control.
Stub logger for tests
Add info about contributing to docs to CONTRIBUTING.md

Encourage more people to contribute to Rails docs by mentioning it in the contribution guide.
Merge pull request #10867 from iHiD/patch-1

Add info about contributing to docs to CONTRIBUTING.md
clearing autoloaded constants triggers routes reloading [Fixes #10685]

Conflicts:
	railties/test/application/loading_test.rb
registers recent patch in the railties CHANGELOG
As we have moved to rails/docrails from lifo/docrails

Changing links to guides.

We are not worried for old versions as GitHub is 
handling the redirects.
Merge pull request #10871 from arunagw/lifo-to-rails

As we have moved to rails/docrails from lifo/docrails
Merge pull request #10561 from Empact/nix-throwresult

Rather than raising ThrowResult when construct_limited_ids_conditions comes up empty, set the relation to NullRelation and rely on its results.
Docfix: Use public interface instead of setting instance variables

Dynamically setting instance variables based on user input probably isn't a great idea. Better to go through the setter methods provided by attr_accessor.
Merge pull request #10874 from rlivsey/patch-1

Docfix: Use public interface instead of setting instance variables
Fix some typos
Merge pull request #10875 from vipulnsward/fix_some_typos_in_as

Fix some typos [ci skip]
Merge pull request #10860 from ka8725/activemodel_log

Ignore activemodel/log/ folder
ActiveRecord::Relation#blank? should `LIMIT 1`

This is an SQL improvement to ActiveRecord::Relation#blank?. Currently,
it calls `to_a` on the Relation, which loads all records in the
association, and calls `blank?` on the loaded Array. There are other
ways, however, to check the emptiness of an association that are far
more performant. `#empty?`, `#exists?` and `#any?` all attach a `LIMIT
1` to the SQL query before firing it off, which is a nice query
improvement. `#blank?` should do the same!

Bonus performance improvements will also happen for `#present?`, which
merely calls the negation of `#blank?`

Signed-off-by: David Celis <me@davidcel.is>
Merge pull request #10539 from davidcelis/ar-sql-improvements

Improve performance of ActiveRecord::Relation#blank?