remove old null.dag file, superseded by null_dag capability

schema/versions/4e009168b3bf_remove_old_null_dag_file.py

+"""remove old null.dag file
+
+Revision ID: 4e009168b3bf
+Revises: 8a027ec917ff
+Create Date: 2021-09-22 13:48:45.063540
+
+"""
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision = "4e009168b3bf"
+down_revision = "8a027ec917ff"
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    op.execute(
+        """
+        DELETE FROM workflow_templates WHERE filename='null.dag'
+        """
+    )
+
+
+def downgrade():
+    op.execute(
+        """
+        INSERT INTO workflow_templates (filename, content, workflow_name) 
+        VALUES ('null.dag', E'JOB null null.condor', 'null') 
+        """
+    )