message: [bugfix] SQLA instance has been deleted
  Related Msg:
  sqlalchemy.orm.exc.ObjectDeletedError: Instance '<PermissionView at
  0x7f10306b0e90>' has been deleted, or its row is otherwise not present.
diff: @@ -141,12 +141,14 @@ def is_granter_pvm(pvm):
  'can_approve'}
  -def set_role(role_name, pvms, pvm_check):
  +def set_role(role_name, pvm_check):
  logging.info("Syncing {} perms".format(role_name))
  + sesh = sm.get_session()
  + pvms = sesh.query(ab_models.PermissionView).all()
  + pvms = [p for p in pvms if p.permission and p.view_menu]
  role = sm.add_role(role_name)
  role_pvms = [p for p in pvms if pvm_check(p)]
  role.permissions = role_pvms
  - sesh = sm.get_session()
  sesh.merge(role)
  sesh.commit()
  @@ -200,24 +202,15 @@ def sync_role_definitions():
  get_or_create_main_db()
  create_custom_permissions()
  - pvms = db.session.query(ab_models.PermissionView).all()
  - pvms = [p for p in pvms if p.permission and p.view_menu]
  -
  - # cleanup
  - pvms_to_delete = [p for p in pvms if not (p.permission and p.view_menu)]
  -
  - for pvm_to_delete in pvms_to_delete:
  - sm.get_session.delete(pvm_to_delete)
  -
  # Creating default roles
  - set_role('Admin', pvms, is_admin_pvm)
  - set_role('Alpha', pvms, is_alpha_pvm)
  - set_role('Gamma', pvms, is_gamma_pvm)
  - set_role('granter', pvms, is_granter_pvm)
  - set_role('sql_lab', pvms, is_sql_lab_pvm)
  + set_role('Admin', is_admin_pvm)
  + set_role('Alpha', is_alpha_pvm)
  + set_role('Gamma', is_gamma_pvm)
  + set_role('granter', is_granter_pvm)
  + set_role('sql_lab', is_sql_lab_pvm)
  if conf.get('PUBLIC_ROLE_LIKE_GAMMA', False):
  - set_role('Public', pvms, is_gamma_pvm)
  + set_role('Public', is_gamma_pvm)
  create_missing_perms()
  