relates #722

...by the bug fixed in 866c3515

Libor Peltan authored 4 years ago and Daniel Salzman committed 4 years ago

When the merged changeset takes less journal chunks than
the original one, the additional chunks remained there
causing malformed or wrong data. Deleting merged changeset
explicity before re-adding it will get rid of possibly
leftover chunks to remain in journal DB.

...in order to avoid wrong SEP bit after KSK versus ZSK change
Also, allow SEP bit setting of already generated key.

The reason for this change is to reduce possible amplification attacks and
other negative effects of long processing loops.

Also most resolvers don't accept multiple jumps without requerying, so this
change should be harmless.