Boards Manager: index was updated twice. Fixed

Author: Federico Fissore

app/src/cc/arduino/contributions/packages/ui/ContributionManagerUI.java

@@ -148,7 +148,6 @@ public void onUpdatePressed() {
       public void run() {
         try {
           setProgressVisible(true, "");
-          installer.updateIndex();
           List<String> downloadedPackageIndexFiles = installer.updateIndex();
           installer.deleteUnknownFiles(downloadedPackageIndexFiles);
           onIndexesUpdated();