Ignore empty header line.

library/network/protocol/http/src/http_header.e

@@ -180,10 +180,12 @@ feature -- Header: adding
             		if line [line.count] = '%R' then
 						line.remove_tail (1)
             		end
+					if not line.is_empty then
 						add_header (line)
 					end
             	end
 			end
+		end
 
 	append_array (a_headers: ARRAY [TUPLE [key: READABLE_STRING_8; value: READABLE_STRING_8]])
 			-- Append array of key,value headers