Reminder email logic broken for untimed events

I was doing some final click-testing for #1013748: Roll a 6.x-1.0 :D ! and noticed a bug. Not worth blocking the release over, but I wanted to document it while it's on my mind.

If you have an untimed event, the logic for not sending reminder emails appears to be broken. There's correctly no UI for this setting (which only works if we know the start time of an event), but somehow it's still ending up in the DB as enabled. So, when you signup, you get a dsm that's lying:

"Signup to Untimed test node confirmed. A confirmation email will be sent shortly containing further information about this Signup untimed. A reminder email will be sent 1 day before the Signup untimed."

I doubt untimed signups are a heavily used feature of this module, but it'd be good to fix this someday. ;)