fetch: do not store peeled tag object names in FETCH_HEAD

fetch: do not store peeled tag object names in FETCH_HEAD

We do not want to record tags as parents of a merge when the user does
"git pull $there tag v1.0" to merge tagged commit, but that is not a good
enough excuse to peel the tag down to commit when storing in FETCH_HEAD.
The caller of underlying "git fetch $there tag v1.0" may have other uses
of information contained in v1.0 tag in mind.

[jc: the test adjustment is to update for the new expectation]

Signed-off-by: Junio C Hamano <gitster@pobox.com>