This change was suggested as Countermeasure 2 in Eclipse Attacks on
Bitcoin's Peer-to-Peer Network, Ethan Heilman, Alison Kendler, Aviv
Zohar, Sharon Goldberg. ePrint Archive Report 2015/263. March 2015.
This mimics Bitcoin Core commit
f68ba3f67bd500a64fb8932c6b41924ddc31d76f