Merge "Stop prefix discovery if an RA prefix arrives in DISCOVERING" am: 1e003f8ef6 am: 75b7cd38b2

Change-Id: If6dd56d2860611586af3c434af3ddc4b6df76ab3
tree: cda2f49d8628181de3eb6dd2f934d91e1e01f932
  1. core/
  2. services/
  3. tests/