GET diffstat for a particular changeset on the changesets REST resource fails (BB-3478)

A GET request (+basic auth header) to https://api.bitbucket.org/1.0/repositories/jaeboston/backofficeready/changesets/4dc2025c88af/diffstat issued by the JIRA Bitbucket connector (https://studio.atlassian.com/browse/BBC-132) returns a 500 status code.