MM-35300 CRT: No mention badge on Threads when user is mentioned in both the root post and a reply post (#17541)

app/notification.go

@@ -191,10 +191,6 @@ func (a *App) SendNotifications(post *model.Post, team *model.Team, channel *mod
 			mac := make(chan *model.AppError, 1)
 			go func(userID string) {
 				defer close(mac)
-				isRootMention := false
-				if rootMentions != nil {
-					_, isRootMention = rootMentions.Mentions[userID]
-				}
 				_, incrementMentions := mentions.Mentions[userID]
 				// if the user was not explicitly mentioned, check if they explicitly unfollowed the thread
 				if !incrementMentions {
@@ -210,7 +206,8 @@ func (a *App) SendNotifications(post *model.Post, team *model.Team, channel *mod
 						return
 					}
 				}
-				_, err := a.Srv().Store.Thread().MaintainMembership(userID, post.RootId, true, !isRootMention && incrementMentions, *a.Config().ServiceSettings.ThreadAutoFollow, userID == post.UserId, userID == post.UserId)
+				_, err := a.Srv().Store.Thread().MaintainMembership(userID, post.RootId, true, incrementMentions, *a.Config().ServiceSettings.ThreadAutoFollow, userID == post.UserId, userID == post.UserId)
+
 				if err != nil {
 					mac <- model.NewAppError("SendNotifications", "app.channel.autofollow.app_error", nil, err.Error(), http.StatusInternalServerError)
 					return