### Describe the issue

Restarting bitcoin, mempool starts filling from scratch.

### Can you reliably reproduce the issue?
#### If so, please list the steps to reproduce below:
1. Wait for mempool to reach for example 3000 transactions
2. Restart bitcoin
3. Watch mempool filling slowly from scratch

### Expected behaviour
Mempool would already contain ~3000 TX on startup

### Actual behaviour
It starts at 0 and fills up slowly with a few per second.

### Screenshots.
http://imgur.com/a/or82d

### What version of bitcoin-core are you using?
Windows x64 0.14rc1 binary from https://bitcoin.org/bin/bitcoin-core-0.14.0/test.rc1/


### Any extra information that might be useful in the debugging process.
I may not be aware of how the mempool.dat thing works and there could just be a misunderstanding.

pool.CalculateDescendants(it, allConflicting);
                }
                BOOST_FOREACH(CTxMemPool::txiter it, allConflicting) {
                    nConflictingFees += it->GetModifiedFee();
                    nConflictingSize += it->GetTxSize();
                }
            } else {
                return state.DoS(0, false,
                        REJECT_NONSTANDARD, "too many potential replacements", false,
                        strprintf("rejecting replacement %s; too many potential replacements (%d > %d)\n",
                            hash.ToString(),
                            nConflictingCount,
                            maxDescendantsToVisit));
            }
            for (unsigned int j = 0; j < tx.vin.size(); j++)
            {
                
                
                
                
                if (!setConflictsParents.count(tx.vin[j].prevout.hash))
                {
                    
                    
                    
                    if (pool.mapTx.find(tx.vin[j].prevout.hash) != pool.mapTx.end())
                        return state.DoS(0, false,
                                         REJECT_NONSTANDARD, "replacement-adds-unconfirmed", false,
                                         strprintf("replacement %s adds unconfirmed input, idx %d",
                                                  hash.ToString(), j));