ttyから `/etc/issue`の前にある改行文字を削除してください。

エラーが発生しました！F_NONLソースコードに示すように、agettyバイナリから絶対に呼び出されないディレクティブがあります。

...
#define F_NONL      (1<<17) /* No newline before issue */
...
/* Parse command-line arguments. */
static void parse_args(int argc, char **argv, struct options *op)
{
    int c;

    enum {
            VERSION_OPTION = CHAR_MAX + 1,
            NOHINTS_OPTION,
            NOHOSTNAME_OPTION,
            LONGHOSTNAME_OPTION,
            HELP_OPTION,
            ERASE_CHARS_OPTION,
            KILL_CHARS_OPTION,
    };
    const struct option longopts[] = {
            {  "8bits",      no_argument,    0,  '8'  },
            {  "autologin",      required_argument,  0,  'a'  },
            ...
            {  "skip-login",     no_argument,    0,  'n'  },
            {  "nonewline",      no_argument,    0,  'N'  },
    while ((c = getopt_long(argc, argv,
               "8a:cC:d:Ef:hH:iI:Jl:L::mnNo:pP:r:Rst:Uw", longopts,
                NULL)) != -1) {
        switch (c) {
        case '8':
            op->flags |= F_EIGHTBITS;
            break;
        case 'a':
            op->autolog = optarg;
            break;
        case 'c':
            op->flags |= F_KEEPCFLAGS;
            break;
        case 'C':
            op->chdir = optarg;
            break;
        case 'd':
            op->delay = atoi(optarg);
            break;
        case 'E':
            op->flags |= F_REMOTE;
            break;
        case 'f':
            op->flags |= F_CUSTISSUE;
            op->issue = optarg;
            break;
        case 'h':
            op->flags |= F_RTSCTS;
            break;
        case 'H':
            fakehost = optarg;
            break;
        case 'i':
            op->flags &= ~F_ISSUE;
            break;
        case 'I':
            init_special_char(optarg, op);
            op->flags |= F_INITSTRING;
            break;
        case 'J':
            op->flags |= F_NOCLEAR;
            break;
        case 'l':
            op->login = optarg;
            break;
        case 'L':
            /* -L and -L=always have the same meaning */
            op->clocal = CLOCAL_MODE_ALWAYS;
            if (optarg) {
                if (strcmp(optarg, "=always") == 0)
                    op->clocal = CLOCAL_MODE_ALWAYS;
                else if (strcmp(optarg, "=never") == 0)
                    op->clocal = CLOCAL_MODE_NEVER;
                else if (strcmp(optarg, "=auto") == 0)
                    op->clocal = CLOCAL_MODE_AUTO;
                else
                    log_err(_("invalid argument of --local-line"));
            }
            break;
        case 'm':
            op->flags |= F_PARSE;
            break;
        case 'n':
            op->flags |= F_NOPROMPT;
            break;
        case 'o':
            op->logopt = optarg;
            break;
        case 'p':
            op->flags |= F_LOGINPAUSE;
            break;
        case 'P':
            op->nice = atoi(optarg);
            break;
        case 'r':
            op->chroot = optarg;
            break;
        case 'R':
            op->flags |= F_HANGUP;
            break;
        case 's':
            op->flags |= F_KEEPSPEED;
            break;
        case 't':
            if ((op->timeout = atoi(optarg)) <= 0)
                log_err(_("bad timeout value: %s"), optarg);
            break;
        case 'U':
            op->flags |= F_LCUC;
            break;
        case 'w':
            op->flags |= F_WAITCRLF;
            break;
        case NOHINTS_OPTION:
            op->flags |= F_NOHINTS;
            break;
        case NOHOSTNAME_OPTION:
            op->flags |= F_NOHOSTNAME;
            break;
        case LONGHOSTNAME_OPTION:
            op->flags |= F_LONGHNAME;
            break;
        case ERASE_CHARS_OPTION:
            op->erasechars = optarg;
            break;
        case KILL_CHARS_OPTION:
            op->killchars = optarg;
            break;
        case VERSION_OPTION:
            printf(_("%s from %s\n"), program_invocation_short_name,
                   PACKAGE_STRING);
            exit(EXIT_SUCCESS);
        case HELP_OPTION:
            usage(stdout);
        default:
            usage(stderr);
        }
    }

whileループに以下のブロックがあるはずですが、欠落しています。

case 'N':
op->flags |= F_NONL;
break;

追加できるマイナーパッチだと思います。完全なソースコードは次のようになります。GitHubまたはkernel.org。