qb_build_uploads directory, created when files are uploaded, is not cleaned when post-execute actions are instructed to clean, such as when "Clean workspace on current node" is selected. The only way to clean the contents of the directory is to choose the "Clean specified directory on current node" option, but this still only cleans out uploaded files within the directory and does not remove it. The qb_build_uploads directory exists whether it has been cleaned out or not.