Tests include:
- Compare the list of files in the resulting archive with the list of
files as tracked in the archived git tree.
- Compare the content of each file with what it should be (git blob
content or the annexed file, respectively).
- Check that the file mode matches the expected file mode for all
archived files.
- Check that the resulting archive has the archived commitID set as a
comment (as `git archive` does as well).
The tests are done for both the "web" endpoints at
`/<user>/<repo>/archive/<git-ref>.{tar.gz,zip}` and the "api-v1"
endpoints at `/api/v1/<user>/<repo>/archive/<git-ref>.{tar.gz,zip}`.
