Bring singleton comm_spawn online.

This commit was SVN r12081.

ompi/communicator/comm_dyn.c

@@ -352,7 +352,7 @@ ompi_comm_start_processes(int count, char **array_of_commands,
     char *base_prefix;
 
     orte_std_cntr_t num_apps, ai;
-    orte_jobid_t new_jobid;
+    orte_jobid_t new_jobid=ORTE_JOBID_INVALID;
     orte_app_context_t **apps=NULL;
 
 
@@ -383,8 +383,11 @@ ompi_comm_start_processes(int count, char **array_of_commands,
     /* we'll just use the prefix from the first member of the app_context array.
      * this shouldn't matter as they all should be the same. it could be NULL, of
      * course (user might not have specified it), so we need to protect against that.
+     *
+     * It's possible that no app_contexts are returned (e.g., during a comm_spawn
+     * from a singleton), so check first
      */
-    if (NULL != apps[0]->prefix_dir) {
+    if (NULL != apps && NULL != apps[0]->prefix_dir) {
         base_prefix = strdup(apps[0]->prefix_dir);
     } else {
         base_prefix = NULL;

ompi/mpi/c/comm_spawn.c

@@ -68,17 +68,6 @@ int MPI_Comm_spawn(char *command, char **argv, int maxprocs, MPI_Info info,
           return OMPI_ERRHANDLER_INVOKE(MPI_COMM_WORLD, MPI_ERR_INFO,
                                         FUNC_NAME);
         }
-
-        /* Do not allow MPI_COMM_SPAWN from a singleton.  This check
-           will be removed when the ORTE 2.0 stuff comes over and
-           Makes This All Better(tm) */
-        if (orte_process_info.singleton) {
-            if (ompi_comm_rank(comm) == root) {
-                opal_show_help("help-mpi-api.txt", "spawn-from-singleton", 
-                               true, FUNC_NAME);
-            }
-            return OMPI_ERRHANDLER_INVOKE(comm, MPI_ERR_ARG, FUNC_NAME);
-        }
     }
    
    rank = ompi_comm_rank ( comm );