Comment 6 for bug 210142

Crucial use-case:

When attempting to push a branch into a Subversion repository that has a commit hook that requires an issue tracking ID for work that was done in Bazaar 'on spec' without a known issue ID, the commits to Subversion will be rejected. Unless the issue ID's can be added retroactively, there is no way to commit to Subversion unless you're willing to lose the entire history.