If you have a tag of a tag of a commit, and the middle tag isn't
otherwise reachable, then "pack-objects --include-tag" will not include
the middle tag, and certain invocations of "clone" will fail. See the
final patch below for the gory details.
The first five patches are just test cleanup and modernization in
preparation (though note that the 3rd one actually fixes a minor bug in
the test script).
[1/5]: t5305: move cleanup into test block
[2/5]: t5305: drop "dry-run" of unpack-objects
[3/5]: t5305: use "git -C"
[4/5]: t5305: simplify packname handling
[5/5]: pack-objects: walk tag chains for --include-tag