fix removing repeated jobs by a repeated job

Two edge cases were missed for removing of repeated jobs.
First, the job in tmp_rj could be removed and accessed in the
LIST_FOREACH_SAFE macro. Second, the job "lastNow" could be
removed and accessed during the search for the next insertion
point.

The master branch was not exposed to the bug, as the code was
already cleaned up in the push to make repeated jobs available
in the client.

src/server/ua_server_worker.c

@@ -231,14 +231,6 @@ UA_Server_addRepeatedJob(UA_Server *server, UA_Job job,
  * - Returns the next datetime when a repeated job is scheduled */
 static UA_DateTime
 processRepeatedJobs(UA_Server *server, UA_DateTime current, UA_Boolean *dispatched) {
-    /* Find the last job that is executed in this iteration */
-    struct RepeatedJob *lastNow = NULL, *tmp;
-    LIST_FOREACH(tmp, &server->repeatedJobs, next) {
-        if(tmp->nextTime > current)
-            break;
-        lastNow = tmp;
-    }
-
     /* Keep pointer to the previously dispatched job to avoid linear search for
      * "batched" jobs with the same nexttime and interval */
     struct RepeatedJob tmp_last;
@@ -264,8 +256,13 @@ processRepeatedJobs(UA_Server *server, UA_DateTime current, UA_Boolean *dispatch
         if((void*)*previousNext != (void*)rj) {
             UA_LOG_DEBUG(server->config.logger, UA_LOGCATEGORY_SERVER,
                          "The current repeated job removed itself");
+            tmp_rj = LIST_FIRST(&server->repeatedJobs);
             continue;
         }
+
+        /* Was tmp_rj removed during the job? */
+        if(LIST_NEXT(rj, next) != tmp_rj)
+            tmp_rj = LIST_FIRST(&server->repeatedJobs);
 #endif
 
         /* Set the time for the next execution */
@@ -284,10 +281,8 @@ processRepeatedJobs(UA_Server *server, UA_DateTime current, UA_Boolean *dispatch
             UA_assert(last_dispatched != &tmp_last);
             prev_rj = last_dispatched;
         } else {
-            /* Find the position by a linear search starting at the first
-             * possible job */
-            UA_assert(lastNow); /* Not NULL. Otherwise, we never reach this point. */
-            prev_rj = lastNow;
+            /* Find the position by a linear search */
+            prev_rj = LIST_FIRST(&server->repeatedJobs);
             while(true) {
                 struct RepeatedJob *n = LIST_NEXT(prev_rj, next);
                 if(!n || n->nextTime >= rj->nextTime)