if (interactive) {
                char *old_index_env = NULL;
-               hold_locked_index(&index_lock, 1);
+               hold_locked_index(&index_lock, LOCK_DIE_ON_ERROR);
 
                refresh_cache_or_die(refresh_flags);
 
         * (B) on failure, rollback the real index.
         */
        if (all || (also && pathspec.nr)) {
-               hold_locked_index(&index_lock, 1);
+               hold_locked_index(&index_lock, LOCK_DIE_ON_ERROR);
                add_files_to_cache(also ? prefix : NULL, &pathspec, 0);
                refresh_cache_or_die(refresh_flags);
                update_main_cache_tree(WRITE_TREE_SILENT);
         * We still need to refresh the index here.
         */
        if (!only && !pathspec.nr) {
-               hold_locked_index(&index_lock, 1);
+               hold_locked_index(&index_lock, LOCK_DIE_ON_ERROR);
                refresh_cache_or_die(refresh_flags);
                if (active_cache_changed
                    || !cache_tree_fully_valid(active_cache_tree))
        if (read_cache() < 0)
                die(_("cannot read the index"));
 
-       hold_locked_index(&index_lock, 1);
+       hold_locked_index(&index_lock, LOCK_DIE_ON_ERROR);
        add_remove_files(&partial);
        refresh_cache(REFRESH_QUIET);
        update_main_cache_tree(WRITE_TREE_SILENT);
                strbuf_stripspace(&sb, 0);
 
        if (signoff)
-               append_signoff(&sb, ignore_non_trailer(&sb), 0);
+               append_signoff(&sb, ignore_non_trailer(sb.buf, sb.len), 0);
 
        if (fwrite(sb.buf, 1, sb.len, s->fp) < sb.len)
                die_errno(_("could not write commit template"));
 
        if (also + only + all + interactive > 1)
                die(_("Only one of --include/--only/--all/--interactive/--patch can be used."));
-       if (argc == 0 && (also || (only && !amend)))
+       if (argc == 0 && (also || (only && !amend && !allow_empty)))
                die(_("No paths with --include/--only does not make sense."));
-       if (argc == 0 && only && amend)
-               only_include_assumed = _("Clever... amending the last one with dirty index.");
        if (argc > 0 && !also && !only)
                only_include_assumed = _("Explicit paths specified without -i or -o; assuming --only paths...");
        if (!cleanup_arg || !strcmp(cleanup_arg, "default"))
        const char *index_file, *reflog_msg;
        char *nl;
        unsigned char sha1[20];
-       struct commit_list *parents = NULL, **pptr = &parents;
+       struct commit_list *parents = NULL;
        struct stat statbuf;
        struct commit *current_head = NULL;
        struct commit_extra_header *extra = NULL;
                if (!reflog_msg)
                        reflog_msg = "commit (initial)";
        } else if (amend) {
-               struct commit_list *c;
-
                if (!reflog_msg)
                        reflog_msg = "commit (amend)";
-               for (c = current_head->parents; c; c = c->next)
-                       pptr = &commit_list_insert(c->item, pptr)->next;
+               parents = copy_commit_list(current_head->parents);
        } else if (whence == FROM_MERGE) {
                struct strbuf m = STRBUF_INIT;
                FILE *fp;
                int allow_fast_forward = 1;
+               struct commit_list **pptr = &parents;
 
                if (!reflog_msg)
                        reflog_msg = "commit (merge)";
-               pptr = &commit_list_insert(current_head, pptr)->next;
+               pptr = commit_list_append(current_head, pptr);
                fp = fopen(git_path_merge_head(), "r");
                if (fp == NULL)
                        die_errno(_("could not open '%s' for reading"),
                        parent = get_merge_parent(m.buf);
                        if (!parent)
                                die(_("Corrupt MERGE_HEAD file (%s)"), m.buf);
-                       pptr = &commit_list_insert(parent, pptr)->next;
+                       pptr = commit_list_append(parent, pptr);
                }
                fclose(fp);
                strbuf_release(&m);
                        reflog_msg = (whence == FROM_CHERRY_PICK)
                                        ? "commit (cherry-pick)"
                                        : "commit";
-               pptr = &commit_list_insert(current_head, pptr)->next;
+               commit_list_insert(current_head, &parents);
        }
 
        /* Finally, get the commit message */