Case activity created with hour=12pm and status completed gives a warning after 12 pm

Create a case activity
Wait until after 12 pm (assuming you are in same time zone as the server civi is running on)
Set the hour to 12 pm (minutes don't matter as long as it's not currently something like 12:10 and you choose 12:14, since then yes that is in the future)
Set the status to completed.
It will give a warning about it being in the future, but it's not.
(This seems to happen with non-case activities too.)