Update expected number to match initial server state

This means it is not reliant on the evaluation engine processing the
dataset. Interestingly, the database state purposely seems to keep
the last task's dataset in preparation explicitly (by having
processing marked as done but having to dataset_status entry).

Author: PGijsbers

tests/test_tasks/test_task_functions.py

@@ -96,7 +96,9 @@ def test_list_tasks_empty(self):
 
     @pytest.mark.uses_test_server()
     def test_list_tasks_by_tag(self):
-        num_basic_tasks = 100  # number is flexible, check server if fails
+        # Server starts with 99 active tasks with the tag, and one 'in_preparation',
+        # so depending on the processing of the last dataset, there may be 99 or 100 matches.
+        num_basic_tasks = 99
         tasks = openml.tasks.list_tasks(tag="OpenML100")
         assert len(tasks) >= num_basic_tasks
         for task in tasks.to_dict(orient="index").values():