add include_hidden option to collection_check_boxes helper
Only use BINARY for mysql case sensitive uniqueness check when column has a case insensitive collation.
Ensure LookupContext in Digestor selects correct variant

Related to: #14242 #14243 14293

Variants passed to LookupContext#find() seem to be ignored, so
I've used the setter instead: `finder.variants = [ variant ]`.

I've also added some more test cases for variants. Hopefully this
time passing tests will mean it actually works.
Completely remove potential global state leaks in ActiveModel tests.

ActiveModel tests can now be run in random order.
Fixes STI when 2+ levels deep.

PR #14052 Added a regression where it was only looking for methods in one
level up, So when the method was defined in a 2+ levels up the
inheritance chain, the method was not found as defined.
register OID for PostgreSQL citex datatype [Troy Kruthoff & Lachlan Sylvester]

citext makes it possible to use AR Hash finders for case-insensitive matching as sql UPPER/LOWER functions are not needed.
Removed unnecessary command "application"
Merge pull request #11616 from arunagw/removed-application-command-rails

Removed command "application"
Merge pull request #14342 from zuhao/eliminate_global_state_leak_in_activemodel_tests

Eliminate global state leaks completely in ActiveModel tests
Merge pull request #12523 from lsylvester/pg_citext

Support for PostgreSQL citext data type.
`change_table` supports `citext`. Follow up to #12523.
comment why we are modifying global state. [ci skip]
Merge pull request #14345 from arthurnn/revert_14052

Fixes STI when 2+ levels deep.
Remove mocking on save, when not necessary
Merge pull request #14353 from arthurnn/remove_small_mock

Remove mocking on save, when not necessary
[ci skip] Add documentation for original_fullpath.
Merge pull request #14291 from laurocaetano/doc-for-original-fullpath

Add documentation for original_fullpath. [ci skip]
MySQL 5.6 and later supports microsecond precision in datetime.

You might want to branch it to include this only for 5.6, but
passing these values to < 5.6 doesn't cause issues either.
Test microsecond on mysql 5.6
Changelog entry for mysql56 microseconds