To pick up the discussion of b1827eb and mastercoin-MSC#286:

With Bitcoin Core 0.10 there is a chance that blocks are stored out of order which can create unexpected behavior or crashes.

We are able to detect out of order stored blocks, but it is still not sure where this check should be done.

#40 moves the check and I tested it with empty datadir as well as a datadir with blocks, but a second test can't hurt.

One point I'm not sure about:

bool CheckForOutOfOrderBlockStorage()
{
    AssertLockHeld(cs_main);
    // ...
}

Is this lock usage correct? I tested it once with LOCK(cs_main); instead and it worked, but it's over my head.