message: clear_directory_contents should be no-op if folder does not exist
diff: @@ -316,6 +316,9 @@ fc::time_point calculate_genesis_timestamp( string tstr ) {
  void clear_directory_contents( const fc::path& p ) {
  using boost::filesystem::directory_iterator;
  + if( !fc::is_directory( p ) )
  + return;
  +
  for( directory_iterator enditr, itr{p}; itr != enditr; ++itr ) {
  fc::remove_all( itr->path() );
  }
  