Pull Request refs are not recreated on re-open.

Issue Summary

When declining a PR, the refs/pull-request/<PR ID> is not recreated when the PR is reopened

Steps to Reproduce

1. Create a pull request
2. Navigate to <Bitbucket shared>/data/repositories/<repo slug>/refs/pull-requests
3. Note the ID of your PR exists
4. Decline the PR and note that the PR ID is gone (expected)
5. Reopen the PR

Expected Results

The directory for the PR is recreated

Actual Results

The directory for the PR is not recreated

Workaround

Pushing any change to the master or source branch before OR after the PR is reopened will cause the directory to be created when the PR is open.