500 error when trying to comment on the initial commit of a repo. (BB-7953)

I get this error when trying to comment on the initial commit of a repo.
POST https://bitbucket.org/api/1.0/repositories/rulemotion/signage-api/changesets/4c4a8420680c4a68a75def3258f13d71f41efc4a/comments 500 (INTERNAL SERVER ERROR) e686e57719d8.js:185