prove write_two_blocks_ok2 (in the hoare-quadruple logic)
prove write_two_blocks_ok2 (in the hoare-quadruple logic)

required introducing an odd rule for hoare logic (CPreOr).

mit-pdos/fscq-impl,mit-pdos/fscq-impl,mit-pdos/fscq-impl,mit-pdos/fscq-impl,mit-pdos/fscq-impl