Because pool.res are shared across locales, if we want to build data package divided by locales, we need a way to control the filter not to us pool.res except for only one of the main one. Otherwise, the pool.res in different data package will be different and conflict and won't be able to build different package that can work together.
currently there are no way to do so except locally modify
to change the 7th arg of generate_tree from True to False, we need a way to control this externally, preferably in the filter file. (but command line flag is also acceptable)
This is needed for any data package usage that create package divided by locale(s).