Add support for the "include-tag" parameter in the "fetch" command in
the fetch-pack/upload-pack protocol v2.
In order to determine which tags to include, only objects pointed to by
refs starting with "refs/tags/" are checked. This restriction is for
performance reasons and to match the behavior of Git (see add_ref_tag()
in builtin/pack-objects.c).
Change-Id: I7d70aa09bcc8a525218ff1559e286c2a610258ca Signed-off-by: Jonathan Tan <jonathantanmy@google.com> Signed-off-by: Jonathan Nieder <jrn@google.com>