[AIRFLOW-2930] Fix celery excecutor scheduler crash (#3784)

Caused by an update in PR #3740.
execute_command.apply_async(args=command, ...)
-command is a list of short unicode strings and the above code pass multiple
arguments to a function defined as taking only one argument.
-command = ["airflow", "run", "dag323",...]
-args = command = ["airflow", "run", "dag323", ...]
-execute_command("airflow","run","dag3s3", ...) will be error and exit.

airflow/executors/celery_executor.py

@@ -82,7 +82,7 @@ def execute_async(self, key, command,
         self.log.info("[celery] queuing {key} through celery, "
                       "queue={queue}".format(**locals()))
         self.tasks[key] = execute_command.apply_async(
-            args=command, queue=queue)
+            args=[command], queue=queue)
         self.last_state[key] = celery_states.PENDING
 
     def sync(self):

tests/executors/dask_executor.py

@@ -55,8 +55,8 @@ def assert_tasks_on_executor(self, executor):
         # start the executor
         executor.start()
 
-        success_command = ['true', ]
-        fail_command = ['false', ]
+        success_command = ['true', 'some_parameter']
+        fail_command = ['false', 'some_parameter']
 
         executor.execute_async(key='success', command=success_command)
         executor.execute_async(key='fail', command=fail_command)

tests/executors/test_celery_executor.py

@@ -34,8 +34,8 @@ def test_celery_integration(self):
         executor.start()
         with start_worker(app=app, logfile=sys.stdout, loglevel='debug'):
 
-            success_command = ['true', ]
-            fail_command = ['false', ]
+            success_command = ['true', 'some_parameter']
+            fail_command = ['false', 'some_parameter']
 
             executor.execute_async(key='success', command=success_command)
             # errors are propagated for some reason

tests/executors/test_local_executor.py

@@ -33,8 +33,8 @@ def execution_parallelism(self, parallelism=0):
         executor.start()
 
         success_key = 'success {}'
-        success_command = ['true', ]
-        fail_command = ['false', ]
+        success_command = ['true', 'some_parameter']
+        fail_command = ['false', 'some_parameter']
 
         for i in range(self.TEST_SUCCESS_COMMANDS):
             key, command = success_key.format(i), success_command