Update isExecuting and isFinished in a way that should make NSOperationQueue happy. Hopefully this fixes a mystery crash bug.

Frameworks/Account/Feedly/Operations/FeedlyOperation.swift

@@ -35,8 +35,7 @@ class FeedlyOperation: Operation {
 		
 		downloadProgress = nil
 		
-		isExecutingOperation = false
-		isFinishedOperation = true
+		updateExecutingAndFinished(false, true)
 	}
 	
 	func didFinish(_ error: Error) {
@@ -58,8 +57,7 @@ class FeedlyOperation: Operation {
 	
 	override func start() {
 		guard !isCancelled else {
-			isExecutingOperation = false
-			isFinishedOperation = true
+			updateExecutingAndFinished(false, true)
 
 			if downloadProgress != nil {
 				DispatchQueue.main.async {
@@ -70,7 +68,7 @@ class FeedlyOperation: Operation {
 			return
 		}
 
-		isExecutingOperation = true
+		updateExecutingAndFinished(true, false)
 		DispatchQueue.main.async {
 			self.main()
 		}
@@ -80,24 +78,30 @@ class FeedlyOperation: Operation {
 		return isExecutingOperation
 	}
 	
-	private var isExecutingOperation = false {
-		willSet {
-			willChangeValue(for: \.isExecuting)
-		}
-		didSet {
-			didChangeValue(for: \.isExecuting)
-		}
-	}
-	
 	override var isFinished: Bool {
 		return isFinishedOperation
 	}
 
-	private var isFinishedOperation = false {
-		willSet {
+	private var isExecutingOperation = false
+	private var isFinishedOperation = false
+
+	private func updateExecutingAndFinished(_ executing: Bool, _ finished: Bool) {
+		let isExecutingDidChange = executing != isExecutingOperation
+		let isFinishedDidChange = finished != isFinishedOperation
+
+		if isFinishedDidChange {
 			willChangeValue(for: \.isFinished)
 		}
-		didSet {
+		if isExecutingDidChange {
+			willChangeValue(for: \.isExecuting)
+		}
+		isExecutingOperation = executing
+		isFinishedOperation = finished
+
+		if isExecutingDidChange {
+			didChangeValue(for: \.isExecuting)
+		}
+		if isFinishedDidChange {
 			didChangeValue(for: \.isFinished)
 		}
 	}