rails/rails — pull request #4213 by amatsuda (2011-12-28 07:00:14+00:00)
Title: AR#where with an Array of 2 elements including a nil

With the following code,

```ruby
Model.where(foo: [1, nil])
```

AR builds an SQL like this:

```sql
WHERE foo IN (1) OR foo IS NULL
```

Here's a tiny patch that makes it like this:

```sql
WHERE foo = 1 OR foo IS NULL
```