mysqdump --master-data=N crashes when SELECT BINLOG_GTID_POS() returns NULL for current master coordinates, for whatever reason

MariaDB [(none)]> show master status;

+------------------+-----------+--------------+------------------+

| File | Position | Binlog_Do_DB | Binlog_Ignore_DB |

+------------------+-----------+--------------+------------------+

| mysql-bin.001552 | 313974469 | | |

+------------------+-----------+--------------+------------------+

MariaDB [(none)]> SELECT BINLOG_GTID_POS("mysql-bin.001552",313974469);

+-----------------------------------------------+

| BINLOG_GTID_POS("mysql-bin.001552",313974469) |

+-----------------------------------------------+

| NULL |

+-----------------------------------------------+

static int

get_gtid_pos(char *out_gtid_pos, int master)

{

  MYSQL_RES *res;

  MYSQL_ROW row;

  int found;

  if (mysql_query_with_error_report(mysql, &res,

                                    (master ?

                                     "SELECT @@GLOBAL.gtid_binlog_pos" :

                                     "SELECT @@GLOBAL.gtid_slave_pos")))

    return 1;

  found= 0;

  if ((row= mysql_fetch_row(res)))

  {

    strmake(out_gtid_pos, row[0], MAX_GTID_LENGTH-1);

    found++;

  }

  mysql_free_result(res);

  return (found != 1);

}

gdb --args /apps/hpbx_db_prod/mysql/bin/mysqldump --single-transaction --default-character-set utf8 --add-drop-table --routines --master-data=2 -uroot -p******* --databases test --socket=/apps/hpbx_db_prod/mysql/mysql_pPBX1.sock

GNU gdb (GDB) Red Hat Enterprise Linux 7.6.1-110.el7

Copyright (C) 2013 Free Software Foundation, Inc.

License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>

This is free software: you are free to change and redistribute it.

There is NO WARRANTY, to the extent permitted by law. Type "show copying"

and "show warranty" for details.

This GDB was configured as "x86_64-redhat-linux-gnu".

For bug reporting instructions, please see:

<http://www.gnu.org/software/gdb/bugs/>...

Reading symbols from /apps/hpbx_db_prod/mariadb-10.2.11-linux-x86_64/bin/mysqldump...done.

(gdb) run

Starting program: /apps/hpbx_db_prod/mysql/bin/mysqldump --single-transaction --default-character-set utf8 --add-drop-table --routines --master-data=2 -uroot ...

[Thread debugging using libthread_db enabled]

Using host libthread_db library "/lib64/libthread_db.so.1".

-- MySQL dump 10.16 Distrib 10.2.11-MariaDB, for Linux (x86_64)

--

-- Host: localhost Database: test

-- ------------------------------------------------------

-- Server version 10.2.11-MariaDB-log

/*!40101 SET @OLD_CHARACTER_SET_CLIENT=@@CHARACTER_SET_CLIENT */;

/*!40101 SET @OLD_CHARACTER_SET_RESULTS=@@CHARACTER_SET_RESULTS */;

/*!40101 SET @OLD_COLLATION_CONNECTION=@@COLLATION_CONNECTION */;

/*!40101 SET NAMES utf8 */;

/*!40103 SET @OLD_TIME_ZONE=@@TIME_ZONE */;

/*!40103 SET TIME_ZONE='+00:00' */;

/*!40014 SET @OLD_UNIQUE_CHECKS=@@UNIQUE_CHECKS, UNIQUE_CHECKS=0 */;

/*!40014 SET @OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS, FOREIGN_KEY_CHECKS=0 */;

/*!40101 SET @OLD_SQL_MODE=@@SQL_MODE, SQL_MODE='NO_AUTO_VALUE_ON_ZERO' */;

/*!40111 SET @OLD_SQL_NOTES=@@SQL_NOTES, SQL_NOTES=0 */;

Program received signal SIGSEGV, Segmentation fault.

strmake (dst=0x7fffffffd550 "", src=0x0, length=1022) at /home/buildbot/buildbot/build/strings/strmake.c:36

36 /home/buildbot/buildbot/build/strings/strmake.c: No such file or directory.

Missing separate debuginfos, use: debuginfo-install glibc-2.17-222.el7.x86_64 libgcc-4.8.5-28.0.1.el7_5.1.x86_64 libstdc++-4.8.5-28.0.1.el7_5.1.x86_64

(gdb) bt

#0 strmake (dst=0x7fffffffd550 "", src=0x0, length=1022) at /home/buildbot/buildbot/build/strings/strmake.c:36

#1 0x0000000000411efa in get_binlog_gtid_pos (out_gtid_pos=<optimized out>, binlog_pos_offset=<optimized out>, binlog_pos_file=<optimized out>)

at /home/buildbot/buildbot/build/client/mysqldump.c:1295

#2 do_show_master_status (mysql_con=<optimized out>, consistent_binlog_pos=1, have_mariadb_gtid=1, use_gtid=0)

at /home/buildbot/buildbot/build/client/mysqldump.c:5115

#3 0x000000000041ba70 in main (argc=1, argv=0xb556a0) at /home/buildbot/buildbot/build/client/mysqldump.c:6094