good job writing this test; it exercises a lot of subtle cases. The
trickiest one is that a hardlink to something that didn't get
extracted should not itself be extracted. In some sense, this is not
the desired behavior (we'd rather restore the file), but it's the best
you can do in a single-pass restore of a tar archive.
The test here should be extended to exercise cpio and newc formats as
well, since their hardlink models are different, which will lead to
different handling of some of these edge cases.
Submitted by: Jaakko Heinonen
MFC after: 30 days
19a4817b26