Add test for ActiveRecord::Relation YAML serialization, for #5303 issue
Improve Errors when Controller Name or Action isn't specfied

These errors occur when, there routes are wrongly defined.

example, the following line would cause a missing :action error

    root "welcomeindex"

Mostly beginners are expected to hit these errors, so lets improve the error message a bit to make their learning experience bit better.
Update security.md

Hi Guys 
I was reading through this guide last night and noticed a small mistake, would be great if you could update it. 
I changed the word 'building' to 'build' in line 20. 
"Web application frameworks are made to help developers building web applications"
Remove order attribute from collector

Ruby 1.8 legacy. Since 1.9 hash preserves insertion order. No need for additional array to achieve this
Array#split preserving the calling array
Array#in_groups: documentation updated
Fix missing line and shadow on static error pages [ci skip]
autoload ChangeColumnDefinition (Fixes #12835)
Speed up Array#split
Ruby 2.0.0p247
Rehearsal ---------------------------------------
old  10.670000   0.150000  10.820000 ( 10.822651)
new   8.520000   0.050000   8.570000 (  8.571825)
----------------------------- total: 19.390000sec

          user     system      total        real
old  10.620000   0.170000  10.790000 ( 10.790409)
new   8.570000   0.110000   8.680000 (  8.686051)
A tiny grammatical fix

[ci skip]
Fixes problem with replacing has_one association record with itself
Load test fixtures where data are needed

Without this, some tests here were not actually testing anything.
Avoid sorting an Array including objects from different Classes

addresses "ArgumentError: comparison of VerySpecialComment with SpecialComment failed" in ActiveRecord::DelegationRelationTest#test_#sort!_delegation_is_deprecated
tidy Active Record CHANGELOG. [ci skip].
Fixed typo in migrations guide

Product model name was pluralized in example in migrations guide.
[ci skip]
Do not count "SHOW CREATE TABLE" queries when testing against mysql
test cases to describe the MySQL boolean behavior.
Unifies mysql and mysql2 casting of booleans.
Prevent the counter cache from being decremented twice

when destroying a record on a has_many :through association.
:destroy method has own counter_cache callbacks.
documentation updated for Hashes [ci skip]