Better handling of headers/trailers.

lib/protocol/http1/body/chunked.rb

@@ -90,8 +90,6 @@ def read_line
 				end
 
 				def read_trailers
-					@headers.trailers!
-
 					while line = read_line
 						# Empty line indicates end of headers:
 						break if line.empty?

lib/protocol/http1/connection.rb

@@ -140,13 +140,17 @@ def write_request(authority, method, path, version, headers)
 				@stream.write("host: #{authority}\r\n")
 
 				write_headers(headers)
+
+				headers.trailers!
 			end
 
 			def write_response(version, status, headers, reason = Reason::DESCRIPTIONS[status])
 				# Safari WebSockets break if no reason is given:
 				@stream.write("#{version} #{status} #{reason}\r\n")
 
 				write_headers(headers)
+
+				headers.trailers!
 			end
 
 			def write_headers(headers)
@@ -357,12 +361,16 @@ def write_body_and_close(body, head)
 			end
 
 			def write_body(version, body, head = false, trailers = nil)
-				if body.nil? or body.empty?
+				if body.nil?
 					write_connection_header(version)
 					write_empty_body(body)
-				elsif length = body.length
+				elsif length = body.length and (VERSION != HTTP11 && trailers.nil?)
 					write_connection_header(version)
 					write_fixed_length_body(body, length, head)
+				elsif body.empty?
+					# Even thought this code is the same as the first clause `body.nil?`, HEAD responses have an empty body but still carry a content length. `write_fixed_length_body` takes care of this appropriately.
+					write_connection_header(version)
+					write_empty_body(body)
 				elsif @persistent and version == HTTP11
 					write_connection_header(version)
 					# We specifically ensure that non-persistent connections do not use chunked response, so that hijacking works as expected.