Merge branch 'jt/fetch-nego-tip'

"git fetch" learned a new option "--negotiation-tip" to limit the set of commits it tells the other end as "have", to reduce wasted bandwidth and cycles, which would be helpful when the receiving repository has a lot of refs that have little to do with the history at the remote it is fetching from. * jt/fetch-nego-tip: fetch-pack: support negotiation tip whitelist