Merge branch 'pt/promisor-lazy-fetch-no-recurse' into jch

The mechanism to avoid recursive lazy-fetch from promisor remotes
was not propagated properly to child "git fetch" processes, which
has been corrected.

Comments?

* pt/promisor-lazy-fetch-no-recurse:
  promisor-remote: prevent lazy-fetch recursion in child fetch

diff --cc promisor-remote.c
Simple merge

diff --cc t/t5616-partial-clone.sh
Simple merge