rebase: handle no common ancestor for inmemory

diff --git a/src/rebase.c b/src/rebase.c
index 93a91545d687ac14754f631cd7ef1dbae4ada244..9f3b6ec6ebcf6b7d7858150baf1dcccdb9475f79 100644 (file)
--- a/src/rebase.c
+++ b/src/rebase.c
@@ -852,6 +852,7 @@ static int rebase_next_inmemory(
        git_tree *current_tree = NULL, *head_tree = NULL, *parent_tree = NULL;
        git_rebase_operation *operation;
        git_index *index = NULL;
+       unsigned int parent_count;
        int error;
 
        *out = NULL;
@@ -859,10 +860,20 @@ static int rebase_next_inmemory(
        operation = git_array_get(rebase->operations, rebase->current);
 
        if ((error = git_commit_lookup(&current_commit, rebase->repo, &operation->id)) < 0 ||
-               (error = git_commit_tree(&current_tree, current_commit)) < 0 ||
-               (error = git_commit_parent(&parent_commit, current_commit, 0)) < 0 ||
-               (error = git_commit_tree(&parent_tree, parent_commit)) < 0 ||
-               (error = git_commit_tree(&head_tree, rebase->last_commit)) < 0 ||
+               (error = git_commit_tree(&current_tree, current_commit)) < 0)
+               goto done;
+
+       if ((parent_count = git_commit_parentcount(current_commit)) > 1) {
+               giterr_set(GITERR_REBASE, "Cannot rebase a merge commit");
+               error = -1;
+               goto done;
+       } else if (parent_count) {
+               if ((error = git_commit_parent(&parent_commit, current_commit, 0)) < 0 ||
+                       (error = git_commit_tree(&parent_tree, parent_commit)) < 0)
+                       goto done;
+       }
+
+       if ((error = git_commit_tree(&head_tree, rebase->last_commit)) < 0 ||
                (error = git_merge_trees(&index, rebase->repo, parent_tree, head_tree, current_tree, &rebase->options.merge_options)) < 0)
                goto done;