Do not shrink communicator when number of failed images is out of bounds.

That the number of images failed is reported incorrectly, may happen when in the finalization stage.
To prevent this, the mpi-error handler now checks for the correct number and on incorrect ones
just exists ok.

This commit should
Fix #390.

Author: vehre

src/mpi/mpi_caf.c

@@ -394,6 +394,11 @@ failed_stopped_errorhandler_function (MPI_Comm* pcomm, int* perr, ...)
       *perr = MPI_SUCCESS;
       return;
     }
+  if (num_failed_in_group > caf_num_images)
+    {
+      *perr = MPI_SUCCESS;
+      return;
+    }
 
   MPI_Comm_group (comm, &comm_world_group);
   ranks_of_failed_in_comm_world = (int *) alloca (sizeof (int)
@@ -451,8 +456,20 @@ failed_stopped_errorhandler_function (MPI_Comm* pcomm, int* perr, ...)
   /* TODO: Consider whether removing the failed image from images_full will be
    * necessary. This is more or less politics. */
   for (i = 0; i < num_failed_in_group; ++i)
-    if (image_stati[ranks_of_failed_in_comm_world[i]] == 0)
-      image_stati[ranks_of_failed_in_comm_world[i]] = STAT_FAILED_IMAGE;
+    {
+      if (ranks_of_failed_in_comm_world[i] >= 0
+          && ranks_of_failed_in_comm_world[i] < caf_num_images)
+        {
+          if (image_stati[ranks_of_failed_in_comm_world[i]] == 0)
+            image_stati[ranks_of_failed_in_comm_world[i]] = STAT_FAILED_IMAGE;
+        }
+      else
+        {
+          dprint ("%d/%d: Rank of failed image %d out of range of images 0..%d.\n",
+                  caf_this_image, caf_num_images, ranks_of_failed_in_comm_world[i],
+                  caf_num_images);
+        }
+    }
 
 redo:
   dprint ("%d/%d: %s: Before shrink. \n", caf_this_image, caf_num_images, __FUNCTION__);