Deleting feature branch confuses history synchronizer

The module Colors, had an empty 7.x-1.x branch.
Then there was a feature branch (called aspilicious_experiment) with a good amount of work done on it.

1. git checkout 7.x-1.x; git merge aspilicious_experiment; git rebase -i #somehash
2. Cleaned up the commit messages, nothing fancy
3. git push origin 7.x-1.x
4. git push origin :aspilicious_experiment

I partially expected the commit counts for the module to drop, since they were effectively doubled between the two branches.
But looking at http://drupal.org/node/1197960/commits, I noticed every commit from before I deleted the feature branch was missing it's branch info, both the orphaned commits as well as those on 7.x-1.x.

After some panicking, I decided it was because I didn't have a master branch. So I made one with a README.txt, then emptied out the other files. Those commits show the branch info on http://drupal.org/node/1197960/commits.

Everything looks right in the repo viewer, and when I clone. It just seems to be the d.o history pages.