As part of the pygame move to bitbucket, we are converting a bug database stored in bugzilla.
Work is progressing on the issues migration:
Bugzilla is more comprehensive compared to bitbucket. So not all things can be migrated from the bugzilla bugs to the bitbucket issues.
Also, the bitbucket API is limited in what it can do. You can't add user comments or add attachments.
To get around the attachments part, I made the migration script create a directory of attachments, and then link to them in the bug text. Then I've extracted the attachments from bugzilla and put them online.
To hack around the lack of comment adding in the bitbucket API, I'm just combining all of the comments into the content text.
Other features bitbucket issues API does not have are priorities, and platforms. The issues features _does_ support priorities, but it doesn't look like the API is set up yet. You can't add platforms (like 'Windows XP SP2') at all it seems. You also can not add free form tags of any sort. Another couple of basic things you can not set with bitbucket issues are the date, and the bug id.
So there you have it. This code worked ok for us.
This code might be a useful start for anyone else wanting to start on a migration. Feel free to go fork it yourself: https://bitbucket.org/illume/bugzilla_bitbucket