strangeness!
it was the cocurrence of the command which was messing it up. i ran
the command several times in a row, each one backgrounded. sure
enough, after a while I got an error "Update: cannot insert duplicate
key into unique index". I don't believe this error was present
before, it barfs only after the record has been duplicated and *then*
updated, because then the primary key is checked for uniqueness.
thus, the record is un-updatable.
I plan to get rid of it using the following method:
1) select the offending records into temp table
2) delete the offending records from original table
3) copy the temp table to stdout, then copy one of those records back in.
4) drop temp table
very strange.