on Linux, posix_spawnp succeeds even if the executable does not exist

pspawnp.c

#include <errno.h>
#include <spawn.h>
#include <stdio.h>
#include <string.h>

int main(void)
{
    extern char **environ;
    char *args[] = {"nexist", NULL};
    pid_t pid;

    if ((errno = posix_spawnp(&pid, args[0], NULL, NULL, args, environ)) != 0) {
        fprintf(stderr, "failed to spawn %s:%s\n", args[0], strerror(errno));
        return 1;
    }
    fprintf(stderr, "successfully spawned %s\n", args[0]);
    return 0;
}