Comment 5 for bug 441125

Also note that because of the "hosted" versus "mirrored" sides of Launchpad, it is possible that the broken data only exists on the hosted side. And thus someone who accesses it who is not able to write to it, cannot see that data.

Even further, it is possible to have broken-but-not-referenced data in a repository, which only shows up during things like 'check' and 'upgrade'. (that is what happened to one of Martin Albisetti's repositories, where it had some broken data from 3+ years back.)

We *could* make upgrade only touch referenced data, but in the presence of stuff like stacked branches, it is technically impossible to verify what the minimal set of referenced data is.

It sounds like it would be best if you could get a copy of the original data, to find out any more details.