mempool accepts doublespending txs

[tpfuemp]

tx checks in mempool accept are incomplete resulting in tx's trying to spend the same inputs twice.

these txs are included in blocktemplate leading to invalid blockdata mota-blocktemplate.txt

using such template for mining fails always with error like this:

ERROR: FetchInputs() : 7ec8dfd7c9 prev tx 5fb7442799 index entry not found
ERROR: AcceptBlock(): Block 704726 contains at least two transactions that uses
the same coin.

[IamLupo]

We discussed this case in a team meeting and I pushed a update to fix this case. Take some time before its will be tested and release.