Bug Report: notes disassociated after history edits

Hi,

We’re migrating a very large old repository to Git (the oldest in continuous development!) and using the notes feature to preserve Svn data like revision IDs and branch information.  We’ve run into what seems like an incomplete feature or bug in that notes get orphaned/disassociated if an old commit is changed (e.g., edit a committer's e-mail or the commit message).

The changed commit and all children commits get sha updates, but the notes remain associated with the original sha.  This can be particularly catastrophic, for example, if an early commit is changed as all notes become orphaned.

I presume this is a bug but perhaps we may be doing something wrong?  Is there a better way to preserve old Svn information that will work with filter-branch?

We want to be able to look up commits by the old Svn commit ID because they are pervasively referenced in commit messages, issue trackers, mailing lists, etc.  We also simply don’t want to lose the data on philosophical grounds as we have a detailed continuous development history that goes back 30+ years.  Thank you in advance for any assistance or insights.

Cheers! Sean