in sftp-client.c:

        if (resume_flag) {
                if (fstat(local_fd, &st) == -1) {
                        error("Unable to stat local file \"%s\": %s",
                            local_path, strerror(errno));
                        goto fail;
                }
                if ((size_t)st.st_size > size) {
                        error("Unable to resume download of \"%s\": "   
                            "local file is larger than remote", local_path);    
 fail:
                        do_close(conn, handle, handle_len);
                        buffer_free(&msg);
                        free(handle);
                        return -1;

in the fail label, local_fd is not closed in case open() call was successful.