"Blob temp file get's removed before it should",
https://bugs.launchpad.net/zodb/+bug/595378

A way this to happen is that a transaction is aborted after the
commit process has started. I don't know how this would happen in
the wild.

In 3.10.3, the ZEO tpc_abort call to the server is changed to be
synchronous, which should address this case. Maybe there's another
case.