git-describe: --long shows the object name even for a tagged commit

git-describe: --long shows the object name even for a tagged commit

This is useful when you want to see parts of the commit object name
in "describe" output, even when the commit in question happens to be
a tagged version.  Instead of just emitting the tag name, it will
describe such a commit as v1.2-0-deadbeef (0th commit since tag v1.2
that points at object deadbeef....).

Signed-off-by: Santi Béjar <sbejar@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>