Format HTTPError.log_message only if args provided

Attempts to fix the [jupyter_server/issues/1503](https://github.com/jupyter-server/jupyter_server/issues/1503) issue

diff --git a/tornado/web.py b/tornado/web.py
index 357c5f1aefd147bd89ddc7be519890faa7ab4899..3003fd8e07a3c113fe38d3a43ec7197b2731b539 100644 (file)
--- a/tornado/web.py
+++ b/tornado/web.py
@@ -2520,8 +2520,6 @@ class HTTPError(Exception):
         self.log_message = log_message
         self.args = args
         self.reason = kwargs.get("reason", None)
-        if log_message and not args:
-            self.log_message = log_message.replace("%", "%%")
 
     def __str__(self) -> str:
         message = "HTTP %d: %s" % (
@@ -2529,7 +2527,8 @@ class HTTPError(Exception):
             self.reason or httputil.responses.get(self.status_code, "Unknown"),
         )
         if self.log_message:
-            return message + " (" + (self.log_message % self.args) + ")"
+            log_message = (self.log_message % self.args) if self.args else self.log_message
+            return message + " (" + log_message + ")"
         else:
             return message