rails/rails — pull request #16521 by jasonpang (2014-08-16 00:12:29+00:00)
Title: Actionpack predicate `performed?` now strictly returns a boolean.

Because `performed?` is a predicate, the convention is to return
a boolean value. The previous implementation returned
an Array of render messages instead of true.

The double bang `!!` operator has been applied around the line of
code to coerce the return value to a boolean.