Re: Multiple fetches when unshallowing a shallow clone

[Jeff King <peff@peff.net>]

On Fri, Dec 04, 2015 at 04:38:16PM -0500, Jason Paller-Rzepka wrote:

> It appears that it happens when the shallow history grows to include a
> commit that's pointed to by a previously unseen tag.  For example,
> when I deepen a checkout of git to depth 8, I hit v2.5.2, and a second
> fetch takes place.

Yeah. The code is in builtin/fetch.c:backfill_tags.

> But why would fetching a tag (or set of tags) merit a depth of zero?
> Doesn't depth 1 mean "give me the the objects, and none of their
> descendants"?  Why use 0?

That comes from this line:

  transport_set_option(transport, TRANS_OPT_DEPTH, "0");

That line blame back to b888d61 (Make fetch a builtin, 2007-09-10),
which isn't incredibly helpful.

I think that comes from the original git-fetch.sh, which had:

  ?*)
          # do not deepen a shallow tree when following tags
          shallow_depth=

Which makes sense. I think the code at that point is not aware that we
just "unshallowed" and can therefore drop the depth parameter
altogether. But I admit I am not all that familiar with the shallow
code.

+cc Duy, who can probably say something way more intelligent about this
off the top of his head. :)

-Peff