Merge branch 'jt/partial-clone-missing-ref-delta-base' into maint

"git fetch" into a lazy clone forgot to fetch base objects that are necessary to complete delta in a thin packfile, which has been corrected. * jt/partial-clone-missing-ref-delta-base: t5616: cover case of client having delta base t5616: use correct flag to check object is missing index-pack: prefetch missing REF_DELTA bases t5616: refactor packfile replacement