Fix to partition selection rules (#1633)

Fix the partition selection rule for the weight to enable merging
when the heard partition weight is higher.

Author: katariinaliehu

source/6LoWPAN/Thread/thread_bootstrap.c

@@ -333,9 +333,14 @@ int thread_bootstrap_partition_process(protocol_interface_info_entry_t *cur, uin
     /*Rule 0: If we are going to form Higher partition than heard we dont try to attach to lower ones
      */
     if (thread_extension_enabled(cur) &&
-        thread_info(cur)->thread_device_mode == THREAD_DEVICE_MODE_ROUTER &&
-        heard_partition_leader_data->weighting < thread_info(cur)->partition_weighting) {
-        return -2;
+        thread_info(cur)->thread_device_mode == THREAD_DEVICE_MODE_ROUTER) {
+        if (heard_partition_leader_data->weighting < thread_info(cur)->partition_weighting) {
+        	tr_debug("Heard a lower weight partition");
+            return -2;
+        }
+        if (heard_partition_leader_data->weighting > thread_info(cur)->partition_weighting) {
+            return 2;
+        }
     }
 
     //Rule 1: A non-singleton Thread Network Partition always has higher priority than a singleton Thread Network Partition