Following code copies console font from tty2 to tty3 and tty3 becomes unreadable

#include <fcntl.h>
#include <sys/ioctl.h>
#include <linux/kd.h>
#include <unistd.h>

int main()
{
   int tty3 = open("/dev/tty3", O_RDWR);
   if (tty3 < 0)
      return 1;
   console_font_op cfo = {};
   cfo.op = KD_FONT_OP_COPY;
   cfo.height = 2 - 1; // from tty2
   ioctl(tty3, KDFONTOP, &cfo);
   close(tty3);
   return 0;
}

Steps to reproduce:
1 Go to tty2 and change font with size different from current. For example, run
setfont UniCyr_8x8
2 Run here compiled code from above
3 Go to tty3 and see it


See also https://github.com/systemd/systemd/issues/2784