Current master (73fc922ed64333d45f18d8a448f30cfa2ae0281e) crashes at the end of processing RPC `gettxoutsetinfo` on OS X:

```
$ ./bitcoind 
Assertion failed: (ok), function Next, file txdb.cpp, line 139.
Abort trap: 6
$ 
```

return Read(DB_LAST_BLOCK, nFile);
}
CCoinsViewCursor *CCoinsViewDB::Cursor() const
{
    CCoinsViewDBCursor *i = new CCoinsViewDBCursor(const_cast<CDBWrapper*>(&db)->NewIterator(), GetBestBlock());
    /* It seems that there are no "const iterators" for LevelDB.  Since we
       only need read operations on it, use a const-cast to get around
       that restriction.  */
    i->pcursor->Seek(DB_COINS);
    
    i->pcursor->GetKey(i->keyTmp);
    return i;
}
bool CCoinsViewDBCursor::GetKey(uint256 &key) const
{
    
    if (keyTmp.first == DB_COINS) {
        key = keyTmp.second;
        return true;
    }
    return false;
}
bool CCoinsViewDBCursor::GetValue(CCoins &coins) const
{
    return pcursor->GetValue(coins);
}
unsigned int CCoinsViewDBCursor::GetValueSize() const