let the sqlite task run without rails
Fix spacing issue
4.0 Release notes should point to 4.0 Changelog
Be assertive about adding `[ci skip]` message
`attibutes` => `attributes`
`implemention` => `implementation`
Pull the RelationMutationTests from cases/relation_test to cases/relation/mutation_test.
Deprecate the delegation of Array bang methods in ActiveRecord::Delegation

The primary means of returning results for Array bang methods is to modify
the array in-place. When you call these methods on a relation, that
array is created, modified, and then thrown away. Only the secondary
return value is exposed to the caller.

Removing this delegation is a straight-forward way to reduce user error
by forcing callers to first explicitly call #to_a in order to expose
the array to be acted on by the bang method.
Example of Join models

In the example of join models, there are five models but in the explanation only consider Category, Post, Comment and Guest.
Client.exists?(1,2,3) and Client.exists?([1,2,3]) does not work

The right command for doing that is Client.exists?id:[1,2,3]
Exists does not work like find method, in find method you can do Person.find(1, 2, 6) or Person.find([7, 17]) but not Person.exists?(1,2,3) or Person.exists?([1,2,3])
Review the changes made on 90155b4e28a3887dce9428e9df150ede3d6c7465
added # or comment
Fix typo in set_callback docs. [ci skip]
Merge pull request #12148 from gzohari/callback-typo

Fix typo in set_callback docs. [ci skip]
Do not use instance variables if they are not reused elsewhere
Fix failure with minitest 5.0.7

Require minitest/mock in test where stub method is needed.

Apparently this was being "imported" by minitest pride plugin, which
previously required "minitest/autorun", that required "minitest/mock",
making the method available by chance.

It has been changed in minitest:
https://github.com/seattlerb/minitest/commit/595ce955c0d89575726d10fc18d2afd8f334bcbe

So we need to make sure we require what we really need where necessary.
Cleanup of excerpt helper

* replaced String concatenation by joining
* separator has default value to '', even it is nil
ensure @model_class is initialized
don't depend on object state when reading fixture files
auto link hm:t fixture join tables like habtm