Tried again, this time with logging on, and with another twist: I did the BARE MINIMUM synch and just did it w/o making any changes. It went through an fsck again, and this time it rebooted and all was well. Then I went and made my typo fix and synched. Worked perfectly!

So then ... might there have been an issue doing an fsck along with another change after it? No idea, but there you have it.