cpp-netlib/cpp-netlib — pull request #347 by daedric (2013-12-12 14:10:28+00:00)
Title: cv-qualifier should be removed before checking the Header concept

C++11 allows this kind of construction:

connection->set_status(Connection::bad_request);
const auto size_to_send = std::to_string(reason.size());
auto headers = { Header{"Content-Length", size_to_send} };
auto range = boost::make_iterator_range(headers);
connection->set_headers(range);
connection->write(reason);

But in the case of an initializer_list, elements are const, then the actual
type tested is "const ValueType" instead of "ValueType".