When releasing and the random zone is the same as one with a release already in progress, recursively find another zone to release in

[whitep4nth3r]

... this is to prevent this:

I did two releases where the random zone was clearly a zone that already had a release in progress. If this happens, we should find another random zone to release in recursively, so that we get feedback when a release is triggered.

(An alternative is to send a message to chat with "a release in that zone is already in progress" but we don't know which random zone was selected behind the scenes so this is pointless)