rails/rails — pull request #7971 by dgraham (2012-10-16 20:37:45+00:00)
Title: Implement HashWithIndifferentAccess#replace so key? works correctly.

After calling `replace` all calls to `key?` return false.

```ruby
hash = HashWithIndifferentAccess.new(a: 42)
hash.key?('a') #=> true
hash.replace(b: 12) #=> {b: 12}
hash.key?('b') #=> false
hash.key?(:b) #=> false
```

This branch adds a simple implementation of replace so key? will work.