Re: [PATCH] git clone depth of 0 not possible.

Junio C Hamano [off-list ref] writes:

I think we need a protocol update to fix this; instead of sending
"Now I want your tips and N commits behind it, please update my
shallow bottom accordingly", which creates the above by giving you Z
and 3 generations back and updates your cut-off point to W, the
receiving end should be able to ask "I have a shallow history that
cuts off at these commits. I want to get the history leading up to
your tips, and also deepen the history further back from my current
cut-off points by N commits", so that you would instead end up with
something like this:

 (you)
     o---o---o---A---B---C---D---E---F---...---W---X---Y---Z

That is, truly "deepen my history by 3".  We could call that "git
fetch --deepen=3" or something.

I take that back.  If you start from

 (upstream)
  ---o---o---o---A---B

 (you)
                 A---B

and you are interested in peeking the history a bit deeper, you
should be able to ask "I have a shallow history that cuts off at
these commits. I want my history deepened by N commits.  I do not
care where your current tips are, by the way." with

    git fetch --deepen=3 

and end up with

 (you)
     o---o---o---A---B

without getting the new history leading to the updated tip at the
upstream.  If you want the new history leading to the updated tip,
you can just say:

    git fetch

without any --depth nor --deepen option to end up with:

 (you)
                 A---B---C---D---E---F---...---W---X---Y---Z

instead.