UpdateSite.updateDirectly (from #692) fails to append ?id=...&version=... to the URL it downloads, preventing a "smart" update center with routing rules from serving appropriate content.

This can be very dangerous; in particular trunk versions of maven-plugin (1.501 as of this writing) have a fatal linkage error when run on 1.480.x which even prevents startup (forces manual recovery). Of course the UI would show a warning about the core version mismatch, but you would not want to call updateAllSites and then programmatically ask to install an unspecified version of this plugin!

Compare DownloadService.generateFragment and the associated downloadService JavaScript.