The same GitHub repository branches get detected and added every time the detection runs

Steps to reproduce:

• Go to Plan Configuration -> Branches, and tick "Automatically manage branches"
• Push a new branch to the GitHub remote repository which is configured in the "Source Repositories" section of the plan
• Wait a few minutes, and Bamboo will detect the new branch. After 5 minutes Bamboo will add the same (duplicate) branch again (and again,..).