From 0ba8f3b4e157d954f41116bc80b9ba668dfb04bc Mon Sep 17 00:00:00 2001
From: Brent Simmons <brent@ranchero.com>
Date: Tue, 3 Sep 2019 22:58:17 -0700
Subject: [PATCH] Call the completion block once and only once from
 FetchRequestOperation. This is a probable fix for #898.

---
 Mac/MainWindow/Timeline/FetchRequestOperation.swift | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/Mac/MainWindow/Timeline/FetchRequestOperation.swift b/Mac/MainWindow/Timeline/FetchRequestOperation.swift
index e171f535f..223b2095b 100644
--- a/Mac/MainWindow/Timeline/FetchRequestOperation.swift
+++ b/Mac/MainWindow/Timeline/FetchRequestOperation.swift
@@ -52,10 +52,14 @@ class FetchRequestOperation {
 		var fetchersReturned = 0
 		var fetchedArticles = Set<Article>()
 		for articleFetcher in articleFetchers {
+			var didCallCompletion = false
 			articleFetcher.fetchArticlesAsync { (articles) in
 				precondition(Thread.isMainThread)
 				if self.isCanceled {
-					completion(self)
+					if !didCallCompletion {
+						didCallCompletion = true
+						completion(self)
+					}
 					return
 				}
 				fetchedArticles.formUnion(articles)