Private plugin update renames directory since 4.4

I’m using a plugin that comes from a self-hosted site which pushes the plugin update information via the plugins_api filter.

Since WP 4.4. a new update results in renaming the directory. Previously this was (example) : ‘/my-plugin/plugin.php’, but now some sort of hash is added, which results in something like ‘/my-plugin-IB4Ya7/plugin.php’ .

The latter part of the name is random and changes every update. I pushed the same update multiple times and every time it’s a different string ( same length and composition though ).

I’m browsing the source to figure out what’s causing this and why. While annoying it provides no direct problems but I would like to understand if this is a bug or a feature.

Anybody can give me some pointers to this, or have seen this happen on other (commercial) plugins? The plugins coming from WordPress.org repository don’t have this behavior.

I maintain the site where the plugin comes from as well. I’ve checked the information it pushes but it’s up to documentation ( the little there is ), and this doesn’t happen in WP 4.3 with the same update and code.