title: dag_id could not be found: dag_id. Either the dag did not exist or it failed to parse after upgrading airflow from 1.7.3 to 1.10.1
body: <p>I upgraded the airflow version from 1.7.3 to 1.10.1. After up-gradation of the scheduler, webserver and workers, the dags have stopped working showing below error on scheduler- </p>
  
  <p>Either the dag did not exist or it failed to parse.</p>
  
  <p>I have not made any changes to the config. While investigating the issue the scheduler logs shows the issue. Earlier the scheduler run the task as - </p>
  
  <p>Adding to queue: <code>airflow run &lt;dag_id&gt; &lt;task_id&gt; &lt;execution_date&gt; --local -sd DAGS_FOLDER/&lt;dag_filename.py&gt;</code></p>
  
  <p>While now it is running with absolute path - </p>
  
  <p>Adding to queue: <code>airflow run &lt;dag_id&gt; &lt;task_id&gt; &lt;execution_date&gt; --local -sd /&lt;PATH_TO_DAGS_FOLDER&gt;/&lt;dag_filename.py&gt;</code>     </p>
  
  <p><code>PATH_TO_DAGS_FOLDER</code> is like <code>/home/&lt;user&gt;/Airflow/dags...</code></p>
  
  <p>which is same as what it is pushing it to workers by since worker is running on some other user it is not able to find the dag location specified. </p>
  
  <p>I am not sure how to tell the worker to look in it's own airflow home dir and not the scheduler one?</p>
  
  <p>I am using <code>mysql</code> as backend and <code>rabbitmq</code> for message passing.</p>