Obgraham,
I've seen an email from the Canadian Embassy in Berne that says what I said.
Starting on November 10, 2016, Canadian citizens, including dual citizens, will need a valid Canadian passport to fly to or transit through Canada.
In order to facilitate the travel of dual Canadian citizens who do not currently have a valid Canadian passport, a short-term measure is available to dual Canadian citizens whose second citizenship is from a visa-exempt country. These dual citizens can apply for a special authorization that will let them board their flight to Canada using their valid non-Canadian passport.
This short-term measure, which will be available until January 31, 2017, is open to dual citizens who have an imminent flight to Canada (leaving in less than ten days) and whose Canadian citizenship can be verified by Immigration, Refugees and Citizenship Canada (IRCC). If approved, the authorization will be valid for four days from the date of travel indicated in the application. Those not eligible for the authorization must contact the nearest Government of Canada office abroad to obtain the appropriate travel document.
It is related to ETA so perhaps it doesn't apply to land crossings - but you would be advised to check.
The IT screwup, as I see it, is that pax were told they were approved (provisionally or not) when they hadn't.