Despite using Update URI Plugin header, WP still tries to fetch the Update notes from WP org

[bedas]

Despite setting a ​Plugin Header Update URI directive WP still will try to fetch the Update information (changelog) from a WP Org plugin.

And when filtering the url with ​update_plugins_{hostname} , it will simply load an instance of the "Add new plugin" screen in the ThickBox loaded when clicking "View version vx.x.x details"

I am quite sure I do not miss anything, as I read through all the (undocumented) new feature announcements.

This is a minimal approach you need to replicate the issue:

• Update plugin header directive to use Update URI: https://domain.tld
• Either hook into update_plugins_{hostname} and pass a version higher than your currently installed one, or
• Hook into pre_set_site_transient_update_plugins and pass a new new_version higher than your currently installed one

Of course make sure you do actually have a remote update to be shown.
==> You could also just edit the database entry of _site_transient_update_plugins to trigger the "has update" alert in the plugins list...

All this makes the Update URI pretty much dysfunctional (in the sense that it is not really useful at all) and the developer still needs to manually filter the ThickBox content for the "View update details" or even for the "Plugin details".
And the documentation about all this is either inexistent or very limited (opened a separate issue about that ​here

IMO, passing a custom Update URI should completely unhook all Callisto the WP Org Api and either not allow to "view details" at all, or at least provide some ways to populate that window with custom details (or at least read from the plugin data, which it does not: it reads from remote).

[alexstine]

Updated description per request here: ​https://wordpress.slack.com/archives/C02QB8GMM/p1698662803176509?thread_ts=1697671642.297739&cid=C02QB8GMM