Ensure we don't abort if a tool cannot send a message - the orte/util/comm library used by tools to query mpirun knows how to handle this situation.

Refs trac:3992

This commit was SVN r29975.

The following Trac tickets were found above:
  Ticket 3992 --> https://svn.open-mpi.org/trac/ompi/ticket/3992

orte/mca/errmgr/default_tool/errmgr_default_tool.c

@@ -105,6 +105,13 @@ static void proc_errors(int fd, short args, void *cbdata)
         return;
     }
 
+    if (ORTE_PROC_STATE_UNABLE_TO_SEND_MSG == caddy->proc_state) {
+        /* do nothing - the util/comm library knows how to handle this */
+        OBJ_RELEASE(caddy);
+        return;
+    }
+
+    /* all other errors require abort */
     orte_errmgr_base_abort(ORTE_ERROR_DEFAULT_EXIT_CODE, NULL);
 
     OBJ_RELEASE(caddy);