message: Infer SQL_LAB QuerySource from referrer
diff: @@ -319,6 +319,8 @@ class Database(
  source = utils.QuerySource.DASHBOARD
  elif "/superset/explore/" in request.referrer:
  source = utils.QuerySource.CHART
  + elif "/superset/sqllab/" in request.referrer:
  + source = utils.QuerySource.SQL_LAB
  sqlalchemy_url, params = DB_CONNECTION_MUTATOR(
  sqlalchemy_url, params, effective_username, security_manager, source
  