308 status code is ‘Permanent Redirect’ (see http://greenbytes.de/tech/webdav/draft-reschke-http-status-308-07.html) and `Rack::Response::Helpers#redirect?` would accept it as a redirection when 308 status is supported by Rack.
we don't need to create a new lambda object every time we do parsing
The bytesize and string length differ in this case, and bytesize is the correct value.
I don't want the helpers module to know that the underlying implementation uses a hash for storing headers. Instead, I've extracted a few methods for manipulating the headers and whoever includes the module can use whatever data structure they want.
this way we can manipulate cookies without depending on the cookies being stored in a hash.