fi-prune-empty: fix?

1 files changed, 18 insertions, 6 deletions

diff --git a/fi-prune-empty/main.go b/fi-prune-empty/main.go
index e56250c..569e3cf 100644
--- a/fi-prune-empty/main.go
+++ b/fi-prune-empty/main.go
@@ -134,7 +134,7 @@ func (h *PruneEmpty) pruneParents(commits []string) []string {
 	var ret []string
 	for _, c := range commits {
 		c = h.fixupMark(c)
-		if !h.subsumedBy(c, commits) {
+		if c != "" && h.subsumedBy(c, commits) {
 			ret = append(ret, c)
 		}
 	}
@@ -155,17 +155,29 @@ func (h *PruneEmpty) CmdCommitEnd(cmd libfastimport.CmdCommitEnd) error {
 	sort.Stable(h.commitFile)
 
 	// decide whether to skip this commit
-	if len(parents) == 1 && TreesEqual(h.trees[parents[0]], h.commitFile) {
-		h.replace[mark] = parents[0]
-		return nil
+	switch len(parents) {
+	case 0:
+		if len(h.commitFile) == 0 {
+			h.replace[mark] = ""
+			return nil
+		}
+		h.commitMeta.From = ""
+		h.commitMeta.Merge = nil
+	case 1:
+		if TreesEqual(h.trees[parents[0]], h.commitFile) {
+			h.replace[mark] = parents[0]
+			return nil
+		}
+		fallthrough
+	default:
+		h.commitMeta.From = parents[0]
+		h.commitMeta.Merge = parents[1:]
 	}
 
 	// remember the commit
 	h.addCommit(mark, parents, h.commitFile)
 
 	// emit the commit
-	h.commitMeta.From = parents[0]
-	h.commitMeta.Merge = parents[1:]
 	if err := h.backend.Do(h.commitMeta); err != nil {
 		return err
 	}