Pyhole sends double messages

[robotoer]

Steps to reproduce:

• Send a pyhole command to pyhole in a direct message via slack.
• See each response line printed twice.
• Send a pyhole command to a different chatroom on slack.
• See each response line printed only once.

[posix4e]

I believe the double message thing is a different bug, but we should have an issue for it anyway. I'm not sure when it happens but it seems live.

[posix4e]

@jk0

[jk0]

@robotoer can you try to reproduce this again? This can happen during a new deployment, where there might have been two instances of pyhole running at once. You might have caught me rolling out an update.