Always drop the least preferred HB peer when adding a new one.

gmaxwell · laanwj · commit da5a16b11dca · 2016-12-02T08:38:02.000+01:00
When a BIP152 HB-mode peer is in the least preferred position and
 disconnects, they will not be by ForNode on the next loop. They
 will continue to sit in that position and prevent deactivating
 HB mode for peers that are still connected.

There is no reason for them to stay in the list if already gone,
 so drop the first element unconditionally if there are too many.

Fixes issue #9163.

Github-Pull: #9199
Rebased-From: ca8549d2bd32f17f8b69d1edbe3f2976fba504b4
diff --git a/src/main.cpp b/src/main.cpp
@@ -510,8 +510,8 @@ void MaybeSetPeerAsAnnouncingHeaderAndIDs(const CNodeState* nodestate, CNode* pf
             CNode* pnodeStop = FindNode(lNodesAnnouncingHeaderAndIDs.front());
             if (pnodeStop) {
                 pnodeStop->PushMessage(NetMsgType::SENDCMPCT, fAnnounceUsingCMPCTBLOCK, nCMPCTBLOCKVersion);
-                lNodesAnnouncingHeaderAndIDs.pop_front();
             }
+            lNodesAnnouncingHeaderAndIDs.pop_front();
         }
         fAnnounceUsingCMPCTBLOCK = true;
         pfrom->PushMessage(NetMsgType::SENDCMPCT, fAnnounceUsingCMPCTBLOCK, nCMPCTBLOCKVersion);

Original file line number	Diff line number	Diff line change
`@@ -510,8 +510,8 @@ void MaybeSetPeerAsAnnouncingHeaderAndIDs(const CNodeState* nodestate, CNode* pf`
`510`	`510`	`CNode* pnodeStop = FindNode(lNodesAnnouncingHeaderAndIDs.front());`
`511`	`511`	`if (pnodeStop) {`
`512`	`512`	`pnodeStop->PushMessage(NetMsgType::SENDCMPCT, fAnnounceUsingCMPCTBLOCK, nCMPCTBLOCKVersion);`
`513`		`- lNodesAnnouncingHeaderAndIDs.pop_front();`
`514`	`513`	`}`
	`514`	`+ lNodesAnnouncingHeaderAndIDs.pop_front();`
`515`	`515`	`}`
`516`	`516`	`fAnnounceUsingCMPCTBLOCK = true;`
`517`	`517`	`pfrom->PushMessage(NetMsgType::SENDCMPCT, fAnnounceUsingCMPCTBLOCK, nCMPCTBLOCKVersion);`