Pipelines branch with braces manual run API error

Summary

Pipelines YML file configuration with a branch inside curly braces is getting an API Post error when doing manual run.

Steps to reproduce:

1. Create a commit with the following changes in bitbucket-pipelines.yml file. (note: push it in the same branch)

#!YAML
 branches:
    "{develop-test1}":
      - step:
          name: Clone
          script:
            - echo "Clone all the things!" 

1. Push the changes then go to the commit's URL (E.g. https://bitbucket.org/username/repository_name/commits/3a33af5aec93fc01f042c3261bf6f5b44f98062b)
2. Click "Run pipeline" on the right side to run it manually on Pipelines.

Expected Result

Pipelines will run manually from the commit's page

Actual Result

Pipelines didn't run and showed an API post error in the browser's console logs. (See screenshot attached)

Workaround

Remove the "{}" curly braces, put only the branch name in your bitbucket-pipelines.yml file.