[2.0.72] Server-join mod downloader caches(?) too aggressively

[thesixthroc]

I've noticed this issue a small fraction of the time when applying server modpack updates, and finally got around to making a report.

It's possible for the Factorio client when joining a multiplayer server to not understand that the newest version of a recently updated mod on the mod portal is able to be downloaded, and this to persist for much longer than the relatively short caching experience by the in-game mod browser.

As you can see in the screenshots below, 'No release' is obtained when joining the server (pictured), despite the v1.0.2 zip that is on the server (pictured) being available on both the mod portal website (pictured) and the ingame mod browser on the same client (not pictured). Unfortunately I lost the session log for this situation and was unable to reproduce it to obtain one.

It seems to happen after repeatedly updating the same mod on the server. When it occurs, it occurs for all users simultaneously — they all see 'No Release' and have to download that mod by other means. It seems to resolve by waiting, If I have to guess I'd say it resolves in 15 minutes, which is long enough to cause pain for large servers doing repeated hotfixes in a row.

(Note in passing: to obtain the 'No Release' error screenshot I had to scroll a long way down. It would be better to put the erroring mods at the top of the list.)