Re: git fetch refs and tags

[Jan Weitzel <J.Weitzel@phytec.de>]

Am Dienstag, den 23.04.2013, 13:25 +0200 schrieb Johan Herland:
> On Tue, Apr 23, 2013 at 12:53 PM, Jan Weitzel <J.Weitzel@phytec.de> wrote:
> > Hello,
> > I have the following problem: I have 2 bare git repositories one has
> > several branches and tags.
> > If I try this in the second repository:
> > git fetch -f ../main.git refs/heads/master:refs/heads/master
> > I'm getting also tags from other branches, if I have an old object from
> > one of the other branches.
> > I would expect to have only tags pointing to master ref. (Although the
> > man pages points to the behaviour regarding dangling objects). Is there
> > a way to avoid this? I only find --no-tags which results in having no
> > tags at all. Or need I git purge to remove the old objects first?
> > My goal is to fetch only specific branches and the related tags.
> 
> AFAIK, Git should only auto-follow tags that are reachable from the
> branches you fetch (in this case master). Are you saying that you get
> tags pointing to other history that is NOT reachable from the master
> branch? (i.e. are you getting tags for which "git merge-base $tag
> master" is not equal to "git rev-parse $tag")?
> 
exactly. I reproduced it by coping a object from an other branch to the
locale repository. This results in fetching the not reachable tags.

> Re-reading the man page, I do see the following:
> 
> "if the repository has objects that are pointed by remote tags that it
> does not yet have, then fetch those missing tags. If the other end has
> tags that point at branches you are not interested in, you will not
> get them."
> 
> This can be interpreted as saying that even unreachable objects in
> your local repo that are pointed to by some remote tag will cause that
> tag to be fetched, and in effect resuscitate the
> previously-unreachable object. If this is indeed how it works, I would
> be tempted to label this a bug in the auto-following behavior, as it's
> probably not what most people would expect. In that case, yes, you
Yes my first understanding of auto-following behaviour was wrong ;)
> should be able to get your desired behavior by first purging all
> unreachable objects. Something like "git gc --prune=now" should do the
> job.
Because I run this by scripts is there a way without porcelain commands?
I saw even git prune is one.
> 
> Hope this helps,
Thanks
Jan
> 
> ...Johan
>