SyntaxWarning: "is" with a literal. (#2924)

Did you mean "=="?

horizons/extscheduler.py

@@ -75,7 +75,7 @@ def tick(self):
 				assert dont_use is elem
 				obj = elem[1]
 				obj.callback()
-				if obj.loops > 0 or obj.loops is -1:
+				if obj.loops > 0 or obj.loops == -1:
 					self.add_object(obj) # re-add object
 			else:
 				break