I am calling pthread_kill(t, 0) to check if a thread has exited.
on old fedora pthread_kill() return 3 on fedora39 it return 0.

Reproducible: Always

Steps to Reproduce:
1. build the following example:
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <unistd.h>
#define NUM_THREADS     5

void *PrintHello(void *threadid)
{
   long tid;
   tid = (long)threadid;
   printf("Hello World! It's me, thread #%ld!\n", tid);
   pthread_exit(NULL);
}

int main (int argc, char *argv[])
{
   pthread_t threads[NUM_THREADS];
   int rc;
   long t;
   for(t=0; t<NUM_THREADS; t++){
      printf("In main: creating thread %ld\n", t);
      rc = pthread_create(&threads[t], NULL, PrintHello, (void *)t);
      if (rc){
         printf("ERROR; return code from pthread_create() is %d\n", rc);
         exit(-1);
      }
   }
   sleep(10);
   for(t=0; t<NUM_THREADS; t++){
      rc = pthread_kill(threads[t], 0);
      if (rc){
         printf("ERROR; return code from pthread_kill() is %d\n", rc);
         exit(-1);
      } else {
         printf("thread: %ld still running\n", threads[t]);
      }
   }

   /* Last thing that main() should do */
   pthread_exit(NULL);
}

2. use make to build
3. run it.
Actual Results:  
jfclere@fedora:~/test$ ./threads 
In main: creating thread 0
In main: creating thread 1
In main: creating thread 2
Hello World! It's me, thread #0!
In main: creating thread 3
Hello World! It's me, thread #1!
Hello World! It's me, thread #2!
In main: creating thread 4
Hello World! It's me, thread #3!
Hello World! It's me, thread #4!
thread: 139819774641856 still running
thread: 139819764156096 still running
thread: 139819753670336 still running
thread: 139819743184576 still running
thread: 139819732698816 still running


Expected Results:  
[root@neo3 test]# ./threads 
In main: creating thread 0
In main: creating thread 1
Hello World! It's me, thread #0!
In main: creating thread 2
Hello World! It's me, thread #1!
In main: creating thread 3
Hello World! It's me, thread #2!
In main: creating thread 4
Hello World! It's me, thread #3!
Hello World! It's me, thread #4!
ERROR; return code from pthread_create() is 3