Comment 3 for bug 1494359

that looks like len(part_nodes) < fi

There should always be as many part_nodes as whatever the fragment index might be - maybe that code is stupid - but I bet it's the ring - can you validate this ring?

https://bugs.launchpad.net/swift/+bug/1452431

or instrument a print there to figure out which part and fragment we're blowing up on?