title: Why is a task stuck and not executed in airflow?
body: <p>I'm trying out airflow with the <code>BigQueryOperator</code>. I thought I would use google composer later on, but I want it running locally first. I have airflow up and running an <code>BashOperator</code> works fine, I can also run <code>airflow test &lt;dag&gt; &lt;task&gt;</code> where <code>task</code> is the big query task I want to run, but when I trigger the DAG from the UI the bigquery task is never queued. Instead they have the <code>REMOVED</code> state and nothing happens. </p>
  
  <p>My DAG definition looks like this:</p>
  
  <pre><code>from airflow import DAG
  from airflow.operators.bash_operator import BashOperator
  from datetime import datetime, timedelta
  from airflow.contrib.operators.bigquery_operator import BigQueryOperator
  
  yesterday = datetime.combine(
      datetime.today() - timedelta(1),
  datetime.min.time())
  
  default_args = {
      'owner': 'airflow',
      'depends_on_past': False,
      'email': ['airflow@example.com'],
      'start_date': yesterday,
      'email_on_failure': False,
      'email_on_retry': False,
      'retries': 1,
      'retry_delay': timedelta(minutes=5),
  }
  
  with DAG(
          'tutorial', default_args=default_args) as dag:
  
  operators
      t1 = BashOperator(
          task_id='print_date',
          bash_command='date')
  
      template_sql = '''
              SELECT 'TOMAS' name, '{{ params.my_value }}' value, "{{ params.my_value2 }}" tables
          '''
  
      sampleBigQuery1 = BigQueryOperator(
          task_id='bq_simple_sql1',
          bql=template_sql,
          use_legacy_sql=False,
          destination_dataset_table='temp_tomas.airflow_1',
          allow_large_results=True,
          params={'my_value': (datetime.now()).strftime("%D %T"),
                  'my_value2': "yolo"},  # getTables()},
          create_disposition='CREATE_IF_NEEDED',
          write_disposition='WRITE_TRUNCATE'
      )
  
      t1 &gt;&gt; sampleBigQuery1
  </code></pre>
  
  <p>So how do I debug a case when it works to run <code>airflow test ...</code> but not when it triggered by scheduler or UI? Is it something that seems to be wrong with what I have here?</p>
  
  <p>Locally I'm using a standard install of airflow with sqllite, but that shouldn't have any impact I think. I am running everything in one python env, so it should be pretty contained.</p>