Fixed HTTP_HEADER.put_raw_header (..) by ignoring any empty line of the argument value.

(note: "%R" is considered as empty line here.)

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

@@ -228,7 +228,9 @@ feature -- Header: merging
             		if line [line.count] = '%R' then
 						line.remove_tail (1)
             		end
-					put_header (line)
+					if not line.is_empty then
+						put_header (line)
+					end
             	end
 			end
 		end