Re: [PATCH 3/5] allow cloning a repository "shallowly"

> Johannes Schindelin <Johannes.Schindelin@gmx.de> writes:
> 
> > By specifying a depth, you can now clone a repository such that
> > all fetched ancestor-chains' length is at most "depth". For example,
> > if the upstream repository has only 2 branches ("A" and "B"), which
> > are linear, and you specify depth 3, you will get A, A~1, A~2, A~3,
> > B, B~1, B~2, and B~3. The ends are automatically made shallow
> > commits.
> >
> > Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
> > ---
> >  fetch-pack.c  |   61 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
> >  git-clone.sh  |   19 +++++++++++++++--
> >  upload-pack.c |   21 ++++++++++++++++++-
> >  3 files changed, 96 insertions(+), 5 deletions(-)
> >
> > diff --git a/fetch-pack.c b/fetch-pack.c
> > index 488adc9..9619d6e 100644
> > --- a/fetch-pack.c
> > +++ b/fetch-pack.c
> >...
> > +		while ((len = packet_read_line(fd[0], line, sizeof(line)))) {
> > +			if (!strncmp("shallow ", line, 8)) {
> > +				if (get_sha1_hex(line + 8, sha1))
> > +					die("invalid shallow line: %s", line);
> > +				/* no need making it shallow if we have it already */
> > +				if (lookup_object(sha1))
> > +					continue;
> > +				register_shallow(sha1);
> > +			}
> > +		}
> > +	}
> 
> I understand "no need making it shallow", but I am not sure if a
> non-NULL return from lookup_object() tells us that.