v13 upgrade issue with Calendar

I have a very practical problem: I’m already on 8.1.1 on my box (I test it for a while before releasing — there was no issue when I upgraded ownCloud on my machine) and I don’t think I can downgrade. Likewise for @usachris and anyone that might have tried v0.13 in the moments before I pulled it. I’m afraid of my own problems if I get out of sync with what I publish.