* If there are more than 3 ecmp instance in same compute node and
  transition happens from non-ecmp to ecmp either due to active-active
  flag change or delay in instance-ip link being processed in oper DB,
  then when the first instance path change is being processed, there
  would already be 3 path, and logic expects ecmp peer path to be
  already present in that case, hence assert.
  Changed to login to count path with ecmp flag set only.
  Added a test case for the same, earlier test case used to verify
  only ecmp transition when there are 2 service instance.
Closes-bug:#140484

Change-Id: I38fcc78405ea7ac557b825951d95b497b5389d49