Merge #8969: Decouple peer-processing-logic from block-connection-logic (#2)

f5b960b Move nTimeBestReceived updating into net processing code (Matt Corallo)
d8670fb Move all calls to CheckBlockIndex out of net-processing logic (Matt Corallo)
d6ea737 Remove network state wipe from UnloadBlockIndex. (Matt Corallo)
fc0c24f Move MarkBlockAsReceived out of ProcessNewMessage (Matt Corallo)
65f35eb Move FlushStateToDisk call out of ProcessMessages::TX into ATMP (Matt Corallo)

src/init.cpp

@@ -1103,6 +1103,10 @@ bool AppInit2(boost::thread_group& threadGroup, CScheduler& scheduler)
         return false;
 #endif
     // ********************************************************* Step 6: network initialization
+    // Note that we absolutely cannot open any actual connections
+    // until the very end ("start node") as the UTXO/block state
+    // is not yet setup and may end up being set up twice if we
+    // need to reindex later.
 
     assert(!g_connman);
     g_connman = std::unique_ptr<CConnman>(new CConnman(GetRand(std::numeric_limits<uint64_t>::max()), GetRand(std::numeric_limits<uint64_t>::max())));