It appears that the allura.tasks.repo_tasks.clone task flushes the Project record at the end, and since that task can take a very long time, any updates (e.g. to project description) get lost when it saves the old project document back to mongo.
I haven't duplicated this in development, but here's what happened on sourceforge:
import_project_infotask ran at 2013/12/17 04:54:38 https://sourceforge.net/nf/admin/task_manager/view/52afd90dc4314373398546ad
I didn't find any other tasks with the specific project_id that completed after 06:07:16, so I believe it's the repo clone task at fault.