diff --git a/superset/tasks/slack_util.py b/superset/tasks/slack_util.py
index 64e992390da3..a646d7df77a8 100644
--- a/superset/tasks/slack_util.py
+++ b/superset/tasks/slack_util.py
@@ -18,15 +18,13 @@
 from io import IOBase
 from typing import cast, Optional, Union
 
+from flask import current_app
 from retry.api import retry
 from slack import WebClient
 from slack.errors import SlackApiError
 from slack.web.slack_response import SlackResponse
 
-from superset import app
-
 # Globals
-config = app.config
 logger = logging.getLogger("tasks.slack_util")
 
 
@@ -37,6 +35,7 @@ def deliver_slack_msg(
     body: str,
     file: Optional[Union[str, IOBase, bytes]],
 ) -> None:
+    config = current_app.config
     client = WebClient(token=config["SLACK_API_TOKEN"], proxy=config["SLACK_PROXY"])
     # files_upload returns SlackResponse as we run it in sync mode.
     if file:
diff --git a/superset/viz.py b/superset/viz.py
index 5dc05edfc98a..006062155903 100644
--- a/superset/viz.py
+++ b/superset/viz.py
@@ -322,7 +322,8 @@ def query_obj(self) -> QueryObjectDict:
         gb = self.groupby
         metrics = self.all_metrics or []
         columns = form_data.get("columns") or []
-        groupby = list(set(gb + columns))
+        # merge list and dedup while preserving order
+        groupby = list(OrderedDict.fromkeys(gb + columns))
 
         is_timeseries = self.is_timeseries
         if DTTM_ALIAS in groupby: