fix(sync): mark blocks which diverge from checkpoint as bad

Resolves flake in `TestSyncCheckpointHead`

Not certain why this was flaky, it would mean that sometimes the forking
tipset would not hit this case.

Signed-off-by: Jakub Sztandera <oss@kubuxu.com>

chain/sync.go

@@ -867,6 +867,9 @@ loop:
 
 	if !ignoreCheckpoint {
 		if chkpt := syncer.store.GetCheckpoint(); chkpt != nil && base.Height() <= chkpt.Height() {
+			for _, b := range incoming.Blocks() {
+				syncer.bad.Add(b.Cid(), NewBadBlockReason(incoming.Cids(), "diverges from checkpoint"))
+			}
 			return nil, xerrors.Errorf("merge point affecting the checkpoing: %w", ErrForkCheckpoint)
 		}
 	}

chain/sync_test.go

@@ -86,6 +86,7 @@ type syncTestUtil struct {
 
 func prepSyncTest(t testing.TB, h int) *syncTestUtil {
 	_ = logging.SetLogLevel("*", "INFO")
+	logging.SetLogLevel("fil-consensus", "ERROR")
 
 	g, err := gen.NewGenerator()
 	if err != nil {
@@ -956,7 +957,7 @@ func TestSyncCheckpointHead(t *testing.T) {
 	tu.loadChainToNode(p2)
 
 	base := tu.g.CurTipset
-	fmt.Println("Mining base: ", base.TipSet().Cids(), base.TipSet().Height())
+	t.Log("Mining base: ", base.TipSet().Cids(), base.TipSet().Height())
 
 	// The two nodes fork at this point into 'a' and 'b'
 	a1 := tu.mineOnBlock(base, p1, []int{0}, true, false, nil, 0, true)
@@ -973,14 +974,15 @@ func TestSyncCheckpointHead(t *testing.T) {
 	b = tu.mineOnBlock(b, p2, []int{1}, true, false, nil, 0, true)
 	b = tu.mineOnBlock(b, p2, []int{1}, true, false, nil, 0, true)
 
-	fmt.Println("A: ", a.Cids(), a.TipSet().Height())
-	fmt.Println("B: ", b.Cids(), b.TipSet().Height())
+	t.Log("A: ", a.Cids(), a.TipSet().Height())
+	t.Log("B: ", b.Cids(), b.TipSet().Height())
 
 	// Now for the fun part!! p1 should mark p2's head as BAD.
 
 	require.NoError(t, tu.mn.LinkAll())
 	tu.connect(p1, p2)
 	tu.waitUntilNodeHasTs(p1, b.TipSet().Key())
+
 	p1Head := tu.getHead(p1)
 	require.True(tu.t, p1Head.Equals(a.TipSet()))
 	tu.assertBad(p1, b.TipSet())