In network node change test, the expected behavior is focused on how many nodes
left in networkDB, besides timing issues, things would also go tricky for a
leave-then-join sequence, if the check (counting the nodes) happened before the
first "leave" event, then the testcase actually miss its target and report PASS
without verifying its final result; if the check happened after the 'leave' event,
but before the 'join' event, the test would report FAIL unnecessary;
This code change would check both the db changes and the node count, it would
report PASS only when networkdb has indeed changed and the node count is expected.
Signed-off-by: David Wang <00107082@163.com>
f499c6b9ec