Re: [Non-Bug] cloning a repository with a default MASTER branch tries to check out the master branch

From: Jeff King <peff@peff.net>
Date: May 24, 2017, 14:19 UTC
Message-ID: <20170524141947.2gguzcvyu6lch373@sigill.intra.peff.net>
In-Reply-To: <76BD8B6A1511438B8CCB79C616F3BC5B@PhilipOakley>

On Wed, May 24, 2017 at 12:24:52AM +0100, Philip Oakley wrote:

Show 15 quoted lines

> > > $ git clone git@github.com:passcod/UPPERCASE-NPM.git
> > > Cloning into 'UPPERCASE-NPM'...
> > > remote: Counting objects: 14, done.
> > > remote: Compressing objects: 100% (11/11), done.
> > > remote: Total 14 (delta 3), reused 14 (delta 3), pack-reused 0
> > > Receiving objects: 100% (14/14), done.
> > > Resolving deltas: 100% (3/3), done.
> > > warning: remote HEAD refers to nonexistent ref, unable to checkout.
> 
> Perhaps here the warning message could include the value of the ref provided
> by the remote's HEAD which would then more clearly indicate to the user what
> was expected.
> 
> I haven't had chance to look at how easy that maybe in the code - perhaps a
> bit of low hanging fruit for someone?

Unfortunately, it can't, because the ref doesn't exist:

  $ git ls-remote git://github.com/passcod/UPPERCASE-NPM.git
  efc7dbfd6ca155d5d19ce67eb98603896062f35a	refs/heads/MASTER
  e60ea8e6ec45ec45ff44ac8939cb4105b16477da	refs/pull/1/head
  f35a73dcb151d336dc3d30c9a2c7423ecdb7bd1c	refs/pull/2/head
  0d9b3a1268ff39350e04a7183af0add912b686e6	refs/tags/V1.0.0
  efc7dbfd6ca155d5d19ce67eb98603896062f35a	refs/tags/V1.0.1

There is no HEAD line at all, so we have no information about it on the client side. Likewise, if you run with GIT_TRACE_PACKET=1, you'll see that the capabilities line does not include a symref marker either.

So if we wanted to improve this, I think the first step would be for the server to start sending symref lines for HEAD, even when it does not resolve to anything.

That would also make a case like this:

  git -C dst.git symbolic-ref refs/heads/does-not-exist
  git clone dst.git local

use "does-not-exist" as the default branch name in our local clone (rather than just falling back to "master", which presumably the other side never plans to use).

-Peff