I really know nothing about git except how to use it to grab a copy of some code from Github. Running that git command in either my bitcoin-abe directory or its parent isn't showing anything, so I must have moved things around enough that git became confused. I can see in my command history where I fetched Abe using "git clone," so I know that's how I originally got it.

I did think to save a slice of the transaction history. I was running Abe in an infinite loop where it was using RPC to fetch the latest blocks/transactions from bitcoind, sleeping 60 seconds, and doing it again. The last block I got successfully was 251552 ("block_tx 251552 21898522") followed by several minutes of successful "mempool tx" commits, the last one being "mempool tx 21898948", then one of my script's 60-second sleeps, then the error I posted above. There were no successful transactions after that last "mempool tx" one.

I have made no local modifications to the code at all.