Fix take_over()

This is a fix for #1852.

We have 70 participants missing a total of $1512.28. Amounts vary from $0.25 to $347.75, with an average of $21.6. The receipts of users are actually public data, so I guess we could publish the whole list.

69 of the participants have a GitHub account connected, so we can @mention them here to notify them once we land this. The last one has a Twitter account that we can use instead.
Hmm, the transfer in question is coming from someone who's still an active user.