We have both the status Closed and Done in our workflow. Closed is used for discarded tasks or stuff that is duplicated, etc.
Previously we just had Done and the option to close an issue when a merge is performed would automatically set the right status. Now that there are two statuses that both signify "Done", Bitbucket chooses the first one (by alphabetic sorting?), which unfortunately is Closed, not Done.
I see now way of changing this default, but maybe there is?