Attempt to clarify code to reduce confusion about side effect of MP_CHECKOK macro.
Attempt to clarify code to reduce confusion about side effect of
MP_CHECKOK macro.

nmav/nss,ekr/nss-old,nmav/nss,nmav/nss,nmav/nss,ekr/nss-old,ekr/nss-old,nmav/nss,ekr/nss-old,nmav/nss,ekr/nss-old,ekr/nss-old,nmav/nss,ekr/nss-old