Don't process multiple local notifications.

Signal/src/AppDelegate.m

@@ -69,6 +69,7 @@ static NSTimeInterval launchStartedAt;
 @property (nonatomic) BOOL hasInitialRootViewController;
 @property (nonatomic) BOOL areVersionMigrationsComplete;
 @property (nonatomic) BOOL didAppLaunchFail;
+@property (nonatomic) BOOL hasReceivedLocalNotification;
 
 @end
 
@@ -525,6 +526,9 @@ static NSTimeInterval launchStartedAt;
         [self handleActivation];
     }];
 
+    // We want to process up to one local notification per activation, so clear the flag.
+    self.hasReceivedLocalNotification = NO;
+
     DDLogInfo(@"%@ applicationDidBecomeActive completed.", self.logTag);
 }
 
@@ -876,6 +880,13 @@ static NSTimeInterval launchStartedAt;
         return;
     }
 
+    // Don't process more than one local notification per activation.
+    if (self.hasReceivedLocalNotification) {
+        OWSFail(@"%@ %s ignoring redundant local notification.", self.logTag, __PRETTY_FUNCTION__);
+        return;
+    }
+    self.hasReceivedLocalNotification = YES;
+
     DDLogInfo(@"%@ %s %@", self.logTag, __PRETTY_FUNCTION__, notification);
 
     [AppStoreRating preventPromptAtNextTest];
@@ -923,6 +934,13 @@ static NSTimeInterval launchStartedAt;
         return;
     }
 
+    // Don't process more than one local notification per activation.
+    if (self.hasReceivedLocalNotification) {
+        OWSFail(@"%@ %s ignoring redundant local notification.", self.logTag, __PRETTY_FUNCTION__);
+        return;
+    }
+    self.hasReceivedLocalNotification = YES;
+
     // The docs for handleActionWithIdentifier:... state:
     // "You must call [completionHandler] at the end of your method.".
     // Nonetheless, it is presumably safe to call the completion handler