Jenkins appears to obsess about knowing what the previous build's ref was. If that ref is unavailable in the current clone, the build fails.

This is prevalent in builds triggered by gerrit, since they will often be from random refs in the history, and not necessarily in any meaningful order.

It would be nice if there was a way to tell Jenkins to not even try to determine what the previous build was, but meanwhile it would just help if the build didn't fall over just because the previous build is unavailable.