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Unless "--branch" was given, clone generally tries to match the local
HEAD to the remote one. For most repositories, this is easy: the remote
tells us which branch HEAD was pointing to, and we call our local
checkout() function on that branch.
When cloning an empty repository, it's a little more tricky: we have
special code that checks the transport's "unborn" extension, or falls back
to our local idea of what the default branch should be. In either case,
we point the new HEAD to that, and set up the branch.* config.
But that leaves one case unhandled: when the remote repository _isn't_
empty, but its HEAD is unborn. The checkout() function is smart enough
to realize we didn't fetch the remote HEAD and it bails with a warning.
But we'll have ignored any information the remote gave us via the unborn
extension. This leads to nonsense outcomes:
- If the remote has its HEAD pointing to an unborn "foo" and contains
another branch "bar", cloning will get branch "bar" but leave the
local HEAD pointing at "master" (or whatever our local default is),
which is useless. The project does not use "master" as a branch.
- Worse, if the other branch "bar" is instead called "master" (but
again, the remote HEAD is not pointing to it), then we end up with a
local unborn branch "master", which is not connected to the remote
"master" (it shares no history, and there's no branch.* config).
Instead, we should try to use the remote's HEAD, even if its unborn, to
be consistent with the other cases.
The reason this case was missed is that cmd_clone() handles empty and
non-empty repositories on two different sides of a conditional:
if (we have any refs) {
fetch refs;
check for --branch;
otherwise, try to point our head at remote head;
otherwise, our head is NULL;
} else {
check for --branch;
otherwise, try to use "unborn" extension;
otherwise, fall back to our default name name;
}
So the smallest change would be to repeat the "unborn" logic at the end
of the first block. But we can note some other overlaps and
inconsistencies:
- both sides have to handle --branch (though note that it's always an
error for the empty repo case, since an empty repo by definition
does not have a matching branch)
- the fall back to the default name is much more explicit in the
empty-repo case. The non-empty case eventually ends up bailing
from checkout() with a warning, which produces a similar result, but
fails to set up the branch config we do in the empty case.
So let's pull the HEAD setup out of this conditional entirely. This
de-duplicates some of the code and the result is easy to follow, because
helper functions like find_ref_by_name() do the right thing even in the
empty-repo case (i.e., by returning NULL).
There are two subtleties:
- for a remote with a detached HEAD, it will advertise an oid for HEAD
(which we store in our "remote_head" variable), but we won't find a
matching refname (so our "remote_head_points_at" is NULL). In this
case we make a local detached HEAD to match. Right now this happens
implicitly by reaching update_head() with a non-NULL remote_head
(since we skip all of the unborn-fallback). We'll now need to
account for it explicitly before doing the fallback.
- for an empty repo, we issue a warning to the user that they've
cloned an empty repo. The text of that warning doesn't make sense
for a non-empty repo with an unborn HEAD, so we'll have to
differentiate the two cases there. We could just use different text,
but instead let's allow the code to continue down to checkout(),
which will issue an appropriate warning, like:
remote HEAD refers to nonexistent ref, unable to checkout
Continuing down to checkout() will make it easier to do more fixes
on top (see below).
Note that this patch fixes the case where the other side reports an
unborn head to us using the protocol extension. It _doesn't_ fix the
case where the other side doesn't tell us, we locally guess "master",
and the other side happens to have a "master" which its HEAD doesn't
point. But it doesn't make anything worse there, and it should actually
make it easier to fix that problem on top.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Git - fast, scalable, distributed revision control system
Git is a fast, scalable, distributed revision control system with an unusually rich command set that provides both high-level operations and full access to internals.
Git is an Open Source project covered by the GNU General Public License version 2 (some parts of it are under different licenses, compatible with the GPLv2). It was originally written by Linus Torvalds with help of a group of hackers around the net.
Please read the file INSTALL for installation instructions.
Many Git online resources are accessible from https://git-scm.com/ including full documentation and Git related tools.
See Documentation/gittutorial.txt to get started, then see
Documentation/giteveryday.txt for a useful minimum set of commands, and
Documentation/git-<commandname>.txt for documentation of each command.
If git has been correctly installed, then the tutorial can also be
read with man gittutorial or git help tutorial, and the
documentation of each command with man git-<commandname> or git help <commandname>.
CVS users may also want to read Documentation/gitcvs-migration.txt
(man gitcvs-migration or git help cvs-migration if git is
installed).
The user discussion and development of Git take place on the Git mailing list -- everyone is welcome to post bug reports, feature requests, comments and patches to git@vger.kernel.org (read Documentation/SubmittingPatches for instructions on patch submission and Documentation/CodingGuidelines).
Those wishing to help with error message, usage and informational message
string translations (localization l10) should see po/README.md
(a po file is a Portable Object file that holds the translations).
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The maintainer frequently sends the "What's cooking" reports that list the current status of various development topics to the mailing list. The discussion following them give a good reference for project status, development direction and remaining tasks.
The name "git" was given by Linus Torvalds when he wrote the very first version. He described the tool as "the stupid content tracker" and the name as (depending on your mood):
- random three-letter combination that is pronounceable, and not actually used by any common UNIX command. The fact that it is a mispronunciation of "get" may or may not be relevant.
- stupid. contemptible and despicable. simple. Take your pick from the dictionary of slang.
- "global information tracker": you're in a good mood, and it actually works for you. Angels sing, and a light suddenly fills the room.
- "goddamn idiotic truckload of sh*t": when it breaks