fixes #3559
fixes #3559

if the `:authority` header is not found, we can try to guess it from
variable `flow.request.pretty_host` as .pop() accepts a fallback
parameter

mitmproxy/mitmproxy,mhils/mitmproxy,Kriechi/mitmproxy,mitmproxy/mitmproxy,Kriechi/mitmproxy,mitmproxy/mitmproxy,mhils/mitmproxy,mitmproxy/mitmproxy,vhaupert/mitmproxy,vhaupert/mitmproxy,mhils/mitmproxy,mhils/mitmproxy,vhaupert/mitmproxy,Kriechi/mitmproxy,mitmproxy/mitmproxy,Kriechi/mitmproxy,vhaupert/mitmproxy,mhils/mitmproxy