Create a tree in CVS including an empty directory. Configure a Jenkins job to check it out, leaving the prune option checked. The build runs but the empty directories are not checked out.
Seems to be a bug in the client. UpdateCommand.pruneEmptyDirectories is called but emptyDirectories is empty; messageSent was called once, but MessageEvent.getMessage was blank.
If you select Show all CVS output then it works, presumably because cvs update: Updating workspace/empty was printed.