message: Do not UnCache entries if they are already known.
  There is no need to do this and instead we let the
  pcoinsTip->Trim() take care of an excess entries in
  the dbcache.
diff: @@ -1221,15 +1221,6 @@ bool AcceptToMemoryPoolWorker(CTxMemPool &pool,
  CCoinsViewMemPool viewMemPool(pcoinsTip, pool);
  view.SetBackend(viewMemPool);
  - // do we already have it?
  - bool fHadTxInCache = pcoinsTip->HaveCoinsInCache(hash);
  - if (view.HaveCoins(hash))
  - {
  - if (!fHadTxInCache)
  - vHashTxnToUncache.push_back(hash);
  - return state.Invalid(false, REJECT_ALREADY_KNOWN, "txn-already-known");
  - }
  -
  // do all inputs exist?
  // Note that this does not check for the presence of actual outputs (see the next check for that),
  // and only helps with filling in pfMissingInputs (to determine missing vs spent).
  