Comment 2 for bug 230902

mwhudson just reported this as well. In his case it was also during the triggering of an auto-pack.

This has the same root cause as the TooManyConcurrentRequests errors: some code that indiscriminately calls foo.unlock() in a finally clause without taking care to preserve the original exception (if any).

I'm attaching a barely-tested patch that I think probably fixes the case that Francis and mwhudson have encountered. I'm not sure if it'll fix the original reporter's bug as well. We really need to grep the entire codebase for unlock() calls in finally blocks and fix them all up.