In 4.2.4, it appears that using a rewhere scope on a has_many relation is broken (or at least, has materially changed from earlier versions).

The following gists demonstrate the issue:

activerecord 4.2.3 ('working' example)

https://gist.github.com/scottohara/08d73351e27adeb6f694

In this example, a rewhere scope on the has_many :comments association arbitrarily overrides the WHERE clause to a different id (ie. -> { rewhere(post_id: 99) }).

The SQL SELECT statement for post.comments is as expected:

SELECT "comments".* FROM "comments" WHERE "comments"."post_id" = 99

activerecord 4.2.4 ('broken' example)

https://gist.github.com/scottohara/70a07172882e067aaa96

This is identical to the above gist, but with the activerecord gem version bumped to 4.2.4.

The presence of the rewhere scope now causes the SQL SELECT statement to lose its WHERE clause entirely; yielding:

SELECT "comments".* FROM "comments"

The same behaviour (as 4.2.4) is present in edge (master).

Is this a regression in 4.2.4, or an expected behaviour change? (and if expected, what would be the correct way to use rewhere in 4.2.4?)