Completion codes 201 and 202 mean the chunk asked for was too big, and the
check for them sat after a call that raises, so a bmc that cannot serve 224
bytes at once failed the fru read rather than being asked for less.
The retry could not terminate either: chunksize // 2 + 2 is 4 for a chunksize
of 4, so the chunksize == 3 guard was unreachable and a bmc that kept refusing
would have been asked for 4 bytes for ever.