mysql_install_db: segfault at tmp_file_prefix check

touch /tmp/1

mysql_install_db --basedir=$opt --datadir=./data --defaults-file=$defaults

#0  0x00000000015b0aea in handle_fatal_signal (sig=0) at /home/midenok/src/mariadb/trunk/src/sql/signal_handler.cc:62

#1  <signal handler called>

#2  0x00000000015b0aea in handle_fatal_signal (sig=0) at /home/midenok/src/mariadb/trunk/src/sql/signal_handler.cc:62

#3  <signal handler called>

#4  __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:50

#5  0x00007f93f9035535 in __GI_abort () at abort.c:79

#6  0x00000000007a232b in __sanitizer::Abort() ()

#7  0x00000000007a09b8 in __sanitizer::Die() ()

#8  0x000000000078789f in __asan::ReportGenericError(unsigned long, unsigned long, unsigned long, unsigned long, bool, unsigned long, unsigned int, bool) ()

#9  0x0000000000751c72 in __interceptor_memcmp.part.319 ()

#10 0x00000000009e17d0 in mysql_rm_tmp_tables () at /home/midenok/src/mariadb/trunk/src/sql/sql_base.cc:8819

#11 0x00000000007c5bbf in mysqld_main (argc=12, argv=0x615000000150) at /home/midenok/src/mariadb/trunk/src/sql/mysqld.cc:5742

#12 0x00000000007b9b92 in main (argc=12, argv=0x7ffe4db84e68) at /home/midenok/src/mariadb/trunk/src/sql/main.cc:25

8819          if (!memcmp(file->name, tmp_file_prefix,

8820                      tmp_file_prefix_length))

8821          {

(gdb) p file->name

$1 = 0x62d00005a420 "1"