rails/rails — pull request #8816 by takkanm (2013-01-08 16:09:07+00:00)
Title: give a Hash Object to static_cache_control instead of a String Object

rack shows a warning message if we give a String Object as of the
version 1.4.3.

https://github.com/chneukirchen/rack/commit/40cb556422d15f6011e86435135298085bf8443c

Warning will not appear in this fix.