Merge branch 'ds/path-walk-filters' into next

The "git pack-objects --path-walk" traversal has been integrated
with several object filters, including blobless and sparse filters.

* ds/path-walk-filters:
  path-walk: support `combine` filter
  path-walk: support `object:type` filter
  path-walk: support `tree:0` filter
  t6601: tag otherwise-unreachable trees
  pack-objects: support sparse:oid filter with path-walk
  path-walk: add pl_sparse_trees to control tree pruning
  path-walk: support blob size limit filter
  backfill: die on incompatible filter options
  path-walk: support blobless filter
  path-walk: always emit directly-requested objects
  t/perf: add pack-objects filter and path-walk benchmark
  pack-objects: pass --objects with --path-walk
  t5620: make test work with path-walk var

diff --cc builtin/pack-objects.c
Simple merge

diff --cc t/helper/test-path-walk.c
index 69676b15a53f730bb7c1005011cd3c64ad3479c4,3f2b50a9aa16bd469be4f18a6b1970484e34981c..4233badb58dc0dcb1e985b7fb1cd831bee999ef7
--- 1/t/helper/test-path-walk.c
--- 2/t/helper/test-path-walk.c
+++ b/t/helper/test-path-walk.c
@@@ -89,8 -95,8 +95,8 @@@ int cmd__path_walk(int argc, const cha
                OPT_END(),
        };
  
 -      setup_git_directory();
 +      setup_git_directory(the_repository);
-       revs.repo = the_repository;
+       repo_init_revisions(the_repository, &revs, NULL);
  
        argc = parse_options(argc, argv, NULL,
                             options, path_walk_usage,