Fix Python linting errors. (#3905)

python/ray/experimental/state.py

@@ -775,7 +775,7 @@ class GlobalState(object):
 
             num_tasks += self.redis_client.zcount(
                 event_log_set, min=0, max=time.time())
-        if num_tasks is 0:
+        if num_tasks == 0:
             return 0, 0, 0
         return overall_smallest, overall_largest, num_tasks
 

python/ray/experimental/ui.py

@@ -97,7 +97,7 @@ def get_sliders(update):
         with out_recursion:
             smallest, largest, num_tasks = ray.global_state._job_length()
             diff = largest - smallest
-            if num_tasks is not 0:
+            if num_tasks != 0:
 
                 # Describes the initial values that the slider/text box
                 # values should be set to.