Builds disappear from jobs that were renamed since the last restart after they've been unloaded (lazy loading of 1.485+).

1. Create a new, pristine Jenkins instance
2. Create a freestyle job 'foo' and save
3. Rename 'foo' to 'bar'
4. Click 'Build Now'
5. Run Jenkins.instance.getItemByFullName('bar')._getRuns().purgeCache() in the script console
6. Go to /job/bar
7. Builds are gone.

Alternatively, build first, then rename:
1. Create a new, pristine Jenkins instance
2. Create a freestyle job 'foo' and save
3. Click 'Build Now'
4. Rename 'foo' to 'bar'
5. Run Jenkins.instance.getItemByFullName('bar')._getRuns().purgeCache() in the script console
6. Go to /job/bar
7. Builds are gone.