Here is my personally successful approach to convert an existing Bitbucket hg repo to a new Bitbucket git repo. In this example, I invented a repo with the name "SimonSays". I used Windows 8.1.
- Python 2.7 (https://www.python.org/downloads/release/python-2717/)
- Git (https://git-scm.com/)
- Use Git Bash
- Conversion script / tool fast-export (https://github.com/frej/fast-export)