core/job: use new job ID when we failed to deserialize job ID

This is for the case when we fail to deserialize job ID.
In job_install_deserialized(), we also check the job type, and that is
for the case when we failed to deserialize the job.
Let's gracefully handle the failure in deserializing the job ID.
This is paranoia, and just for safety. Should not change any behavior.

src/core/job.c

@@ -292,6 +292,10 @@ int job_install_deserialized(Job *j) {
                 return log_unit_debug_errno(j->unit, SYNTHETIC_ERRNO(EEXIST),
                                             "Unit already has a job installed. Not installing deserialized job.");
 
+        /* When the job does not have ID, or we failed to deserialize the job ID, then use a new ID. */
+        if (j->id <= 0)
+                j->id = manager_get_new_job_id(j->manager);
+
         r = hashmap_ensure_put(&j->manager->jobs, NULL, UINT32_TO_PTR(j->id), j);
         if (r == -EEXIST)
                 return log_unit_debug_errno(j->unit, r, "Job ID %" PRIu32 " already used, cannot deserialize job.", j->id);