git: Add some tests for annotated tag deletion
git: Add some tests for annotated tag deletion

Added a couple of tests for annotated tag deletion:

* The first one is a general test and should work regardless of the
fixture used - the tag object could possibly be packed, so we do a prune
*and* a repack operation before testing to see if the object was GCed
correctly.

* The second one actually creates the tag to be deleted, so that the tag
object gets created as a loose, unpacked object. This is so we can
effectively test that purning unpacked objects is now working 100%
correctly (this was failing before because tag objects were not
supported for walking).

Signed-off-by: Chris Marchesi <1559339698d4b91062141e6c67af7c94ca1d6f09@vancluevertech.com>

go-git/go-git,go-git/go-git,src-d/go-git,mcuadros/go-git,src-d/go-git,mcuadros/go-git