Forum .LRN Q&A: deleting event in calendar within dotlrn

I partially reported the bug in openforce's site, but then I couldn't
edit or add comments so I am writing the full report here.

trying to delete a recurring event in a class calendar, I get "page
does not exist"

The page is
/public/e-learning/dotlrn-demo/dotlrn/classes/electrical-and-information-engineering/ebus5002-e-commerce-application-frameworks/ebus5002-e-commerce-application-frameworks/cal-item-delete?cal_item_id=6812&return_url=../%22

so you can see that the URI is not complete, isn't it too long due to
the class names?

I am using PG and the standalone calendar works fine (outside dotlrn)