Fix srun -c and --threads-per-core imply --exact

In 21.08, srun --cpus-per-task and threads-per-core wer supposed to
imply --exact. This worked when that new behavior was introduced, but
was regressed by commit 5154ed2 before 21.08 was released. That
commit did not handle setting --exact in step_req if -c was also set.

Bug 12909

NEWS

@@ -36,6 +36,8 @@ documents those changes that are of interest to users and administrators.
  -- Fix writing to Xauthority files on root_squash NFS exports, which was
     preventing X11 forwarding from completing setup.
  -- Fix regression in 21.08.0rc1 that broke --gres=none.
+ -- Fix srun --cpus-per-task and --threads-per-core not implicitly setting
+    --exact. It was meant to work this way in 21.08.
 
 * Changes in Slurm 21.08.4
 ==========================

src/srun/libsrun/launch.c

@@ -182,8 +182,6 @@ static job_step_create_request_msg_t *_create_job_step_create_request(
 		step_req->flags |= SSF_EXCLUSIVE;
 	if (opt_local->overcommit)
 		step_req->flags |= SSF_OVERCOMMIT;
-	if (!srun_opt->exact)
-		step_req->flags |= SSF_WHOLE;
 	if (opt_local->no_kill)
 		step_req->flags |= SSF_NO_KILL;
 	if (srun_opt->interactive) {
@@ -405,6 +403,13 @@ static job_step_create_request_msg_t *_create_job_step_create_request(
 
 	step_req->container = xstrdup(opt_local->container);
 
+	/*
+	 * This must be handled *after* we potentially set srun_opt->exact
+	 * above.
+	 */
+	if (!srun_opt->exact)
+		step_req->flags |= SSF_WHOLE;
+
 	return step_req;
 }