Either the problem was caused by leaving the old dependency package libwebp while reinstalling purple-protocol-plugin, or the autobuilder did something that borked the plugin. Unfortunately, I won't have my phone until the weekend, so I can't test the packages in extras-devel till then.
If you have installed the debs posted before and want to install the ones from extras devel, uninstall both purple-telegram-plugin and libwebp before reinstalation.