Forum .LRN Q&A: Re: # in file-storage URLs has to go. Existing links will break.
He pointed me here: https://openacs.org/forums/message-view?message_id=174911
Would also fix this bug: https://openacs.org/bugtracker/openacs/bug?bug%5fnumber=1518
P.S. On a related note: Vienna showed their modifications to .LRN in Heidelberg on Friday and a few people commented on the sanity of using unique ids for communities'/courses' rather than what we have now.