The test plugin's only purpose is to expose a dummy Test button in the main window, which clutters the GUI for end-users. Attached are trivial patches for f17, f18 & rawhide to disable the test plugin installation in sylpheed.spec.
Created attachment 699025 [details] patch for rawhide
Created attachment 699026 [details] patch for f18
Created attachment 699027 [details] patch for f17
Fine with me, however I don't think it justifies an update in a stable release, so I will only update rawhide. For the stable releases, I will change it in git, but not build it.
http://koji.fedoraproject.org/koji/taskinfo?taskID=5026182