Fix incremental backup exports.

Signal/src/util/Backup/OWSBackupLazyRestore.swift

@@ -73,6 +73,15 @@ public class BackupLazyRestore: NSObject {
         return backup.backupImportState == .inProgress
     }
 
+    @objc
+    public func clearCompleteAndRunIfNecessary() {
+        AssertIsOnMainThread()
+
+        isComplete = false
+
+        runIfNecessary()
+    }
+
     @objc
     public func runIfNecessary() {
         AssertIsOnMainThread()