Fix updating root directories in file system navigation pane

We also need to update the static cache of the root directories and
their properties, otherwise it will be wrong for file system panes that
are opened afterwards.

Change-Id: Iaf96f2728132e7c2f349095b347b13f833ccc732
Reviewed-by: Tobias Hunger <tobias.hunger@qt.io>
Reviewed-by: Florian Apolloner <florian@apolloner.eu>

src/plugins/projectexplorer/foldernavigationwidget.cpp

@@ -441,6 +441,8 @@ void FolderNavigationWidgetFactory::insertRootDirectory(const RootDirectory &dir
     const int index = rootIndex(directory.id);
     if (index < 0)
         m_rootDirectories.append(directory);
+    else
+        m_rootDirectories[index] = directory;
     emit m_instance->rootDirectoryAdded(directory);
 }