rails/rails — pull request #14649 by seanpdoyle (2014-04-08 21:27:25+00:00)
Title: Make `NilClass` quack like `to_s` formattable objects

`nil` would ignore arguments for `to_s` in order to quack like Date objects (and other objects whose `to_s` accepts a format).

```ruby
date = nil
date.to_s #=> ""
date.to_s(:short) #=> ""
date.to_s(:long) #=> ""
```