Bug: .gitignore rules are not handled as one might expect

I looked but I couldn't find this exact issue but it's related to the various .gitignore issues I'm sure. I'm not sure if this is an issue with satis (probably not) or with composer itself but the following rules in gitignore are ignored or misinterpreted because when creating archive files they all disappear completely (instead of excluding them from the first ignore rule):

/www/wp-content/*
!/www/wp-content/index.php
!/www/wp-content/themes/
!/www/wp-content/plugins/
!/www/wp-content/languages/

I.e. the resulting tar archive file contains an empty wp-content folder.

EDIT: it works as expected for files, but not folders.