Merge branch 'jt/connectivity-check-optim-in-partial-clone'

Simplify the commit ancestry connectedness check in a partial clone
repository in which "promised" objects are assumed to be obtainable
lazily on-demand from promisor remote repositories.

* jt/connectivity-check-optim-in-partial-clone:
  connected: always use partial clone optimization

diff --cc builtin/clone.c
Simple merge

diff --cc builtin/fetch.c
Simple merge

diff --cc connected.c
Simple merge