Creating tags from the UI sends two empty "push" "changes" in webhook payload

Steps to repro:

1. Go to a commit, click on the "+" icon and add a new tag.

A webhook is delivered with an empty push.changes array.

Now, create a tag and push from the command line with git tag foo; git push --tags. A webhook is delivered with push.changes[0].new.type: "tag" and the name of the tag as well.

I expect the webhook payload to include this data when I create a tag from the UI as well. Not getting this data makes it impossible for my CI system to trigger anything when users tag things from the BitBucket UI.