At least, updating to async-http 0.56.0 or later will satisfy dependency. https://rubygems.org/gems/async-http/versions/0.56.0
async-http 0.56.0 or later requires protocol-http >= 0.22.0 < 0.23, but ruby-protocol-http 0.22.5-1 is packaged in sid. It also adds new development dependency for localhost, but ruby-localhost is already packaged in sid.
