client: fix relative paths

client/response_handler.py

@@ -256,7 +256,7 @@ class HTMLDownloadHandler(DownloadHandler):
             if img_src[0] == "/":
                 img_src = f"http://{self.cmd.host}{img_src}"
             else:
-                img_src = os.path.join(base_url, img_src)
+                img_src = parser.absolute_url(base_url, img_src)
 
         if parsed.hostname is None or parsed.hostname == self.cmd.host:
             port = self.cmd.port