This has a similar intent as the go code, but not totally equal. For
the go code we want to ensure that the vendored code is up-to-date,
while here we want to ensure that `cargo vendor` actually works.
We happened to release a few tarballs where `cargo vendor` didn't work
and it causes some pain for downstream maintainers.
Related: #2159
Signed-off-by: Fabiano Fidêncio <fidencio@redhat.com>
Otherwise `make install` run from the top directory would just fail as
the target is not defined.
Fixes: #1149
Signed-off-by: Fabiano Fidêncio <fidencio@redhat.com>
