Exercise Completions wiped on the wrong date

If a completion is marked at a certain time (unsure when) they all seem to get wiped. I think this may have to do with the fact that we are checking for wipes server side using UTC rather than localized time.

First step here would be finding a way to successfully reproduce it.

Start by finding how the server decides when exercise completions should be wiped and reproduce the failure around a local-date boundary. Compare the server-side UTC behavior with the user's localized date; done means a completion is not removed on the wrong local date and the original reproduction no longer fails.

Written by the indexing model from the issue text.