Merge branch 'bk/refresh-missing-ok-in-merge-recursive'

Allow "merge-recursive" to work in an empty (temporary) working tree again when there are renames involved, correcting an old regression in 1.7.7 era. * bk/refresh-missing-ok-in-merge-recursive: merge-recursive.c: tolerate missing files while refreshing index read-cache.c: extend make_cache_entry refresh flag with options read-cache.c: refactor --ignore-missing implementation t3030-merge-recursive: test known breakage with empty work tree