In Tor 0.2.2.14-alpha, we added two bugs: A) The LastWritten element of our state became the time of the *previous* time we wrote the file, rather than the time of this writing B) When we fail to write the state file, we set LastWritten to -1, which is no good when we hand it to format_iso_time() in read_bandwidth_usage(). This bug was discovered while looking at legacy/trac#2077.