* All the component nh member of a composite NH are policy disabled
  nexthop, since composite NH itself is policy enabled and there is
  no need for component member to policy disabled. When a transition
  happens from non-ecmp to ecmp, local interface nexthop could be
  added with policy enabled flag, and finding of the nexthop inside
  composite NH would fail since we always search for policy disabled
  nh inside composite NH. Since nexthop lookup fails flow ecmp index
  would not be set, resulting in drop
  Unit test added to verify the case where transition happens from
  non-ecmp to ecmp with local nexthop pre-existing
Closes-bug:#1381978

Change-Id: Iba53ae69c9bbdf8e796ee56d77b0a961b2f4ebf4
Merge "* All the component nh member of a composite NH are policy disabled   nexthop, since composite NH itself is policy enabled and there is   no need for component member to policy disabled. When a transition   happens from non-ecmp to ecmp, local interface nexthop could be   added with policy enabled flag, and finding of the nexthop inside   composite NH would fail since we always search for policy disabled   nh inside composite NH. Since nexthop lookup fails flow ecmp index   would not be set, resulting in drop   Unit test added to verify the case where transition happens from   non-ecmp to ecmp with local nexthop pre-existing Closes-bug:#1381978" into R2.0