X fix

wcfs/internal/zdata/δftail.go

@@ -238,7 +238,9 @@ func (δFtail *ΔFtail) Update(δZ *zodb.EventCommit) (_ ΔF, err error) {
 	δF := ΔF{Rev: δB.Rev, ByFile: make(map[zodb.Oid]*ΔFile)}
 
 	// take btree changes into account
+//	fmt.Printf("δB.ΔByRoot: %v\n", δB.ΔByRoot)
 	for root, δt := range δB.ΔByRoot {
+//		fmt.Printf("root: %v   δt: %v\n", root, δt)
 		files := δFtail.fileIdx[root]
 		if len(files) == 0 {
 			panicf("BUG: ΔFtail: root<%s> -> ø files", root)
@@ -307,6 +309,10 @@ func (δFtail *ΔFtail) Update(δZ *zodb.EventCommit) (_ ΔF, err error) {
 		}
 
 		for root, inblk := range zt.inroot {
+			if len(inblk) == 0 {
+				continue
+			}
+//			fmt.Printf("root: %v   inblk: %v\n", root, inblk)
 			files := δFtail.fileIdx[root]
 			for file := range files {
 				δfile, ok := δF.ByFile[file]
@@ -320,6 +326,8 @@ func (δFtail *ΔFtail) Update(δZ *zodb.EventCommit) (_ ΔF, err error) {
 		}
 	}
 
+//	fmt.Printf("-> δF: %v\n", δF)
+
 	δFtail.vδF = append(δFtail.vδF, δF)
 	return δF, nil
 }

wcfs/internal/zdata/δftail_test.go

@@ -175,6 +175,8 @@ func testΔFtail(t_ *testing.T, testq chan ΔFTestEntry) {
 		xat[commit.At] = fmt.Sprintf("at%d", i)
 		t.Logf("# → @%s (%s)  δT%s  δD%s\t; %s", xat[commit.At], commit.At, xbtreetest.KVTxt(test.δblkTab), test.δdataTab, tTxt)
 
+//		fmt.Printf("Zinblk: %v\n", Zinblk)
+
 		// update δftail
 		δF, err := δftail.Update(commit.ΔZ);  X(err)