Update utils.py

Prevent exponential_backoff() to crash with an Vverflow Error

jupyterhub/utils.py

@@ -171,7 +171,15 @@ async def exponential_backoff(
         # add some random jitter to improve performance
         # this prevents overloading any single tornado loop iteration with
         # too many things
+        # Except Overflow Error. Otherwise start_wait * scale will be too big at some point.
+        try:
+            if scale == 0:
+                dt = min(max_wait, remaining))
+            else:
                 dt = min(max_wait, remaining, random.uniform(0, start_wait * scale))
+        except OverflowError:
+            scale = 0
+            dt = min(max_wait, remaining)
         scale *= scale_factor
         await gen.sleep(dt)
     raise TimeoutError(fail_message)