How to migrate from BitBucket to GitHub

Short notes on what we did to migrate from BitBucket to GitHub, mainly not to lose this information.

1. create repo on github (from web interface)

2. move the repository, going through a bare repository in a local folder:

   git clone --mirror https://bitbucket.org/aiida_team/aiida_core.git
   cd aiida_core.git
   git remote set-url --push origin git@github.com:giovannipizzi/aiida_core_test.git
   git push --mirror
   

3. move issues: This must be done only once, starting from a new repository without issues or pull requests, to keep the numbering. If something goes wrong, then delete the repository and start again from the very beginning.

We used the script from this repository, but we modified it to keep a mapping between different usernames, and to reassign assignees for open issues (code is in the helpers_aiida repository accessible to AiiDA developers, folder /helpers/migration_to_github/run_migration.sh).