message: Update down_revision to fix migrations
diff: """Add published column to dashboards
  Revision ID: d6ffdf31bdd4
  -Revises: 45e7da7cfeba
  +Revises: b4a38aa87893
  Create Date: 2018-03-30 14:00:44.929483
  """
  # revision identifiers, used by Alembic.
  revision = "d6ffdf31bdd4"
  -down_revision = "d7c1a0d6f2da"
  +down_revision = "b4a38aa87893"
  from alembic import op
  import sqlalchemy as sa
  