"fatal: reference is not a tree:" on git checkout <branch>

Hi,

Reproduce:

$ git clone https://github.com/cms-sw/cmsdist.git
$ git branch -a | grep devel-gcc48
remotes/origin/IB/CMSSW_7_0_X/devel-gcc48
$ git checkout IB/CMSSW_7_0_X/devel-gcc48
fatal: reference is not a tree: IB/CMSSW_7_0_X/devel-gcc48

It has stopped to work with the last pull request. All the references on Google 
talk about submodules, which I don't use. Any ideas what could be causing this
issue?

You can get into detached state by:
$ git checkout origin/IB/CMSSW_7_0_X/devel-gcc48 

You also can checkout a branch by doing:
$ git clone -b IB/CMSSW_7_0_X/devel-gcc48 https://github.com/cms-sw/cmsdist.git
$ git branch
* IB/CMSSW_7_0_X/devel-gcc48

Thanks,
david

On Fri, Jul 26, 2013 at 4:52 PM, David Abdurachmanov
[off-list ref] wrote:

Hi,

Reproduce:

$ git clone https://github.com/cms-sw/cmsdist.git
$ git branch -a | grep devel-gcc48
remotes/origin/IB/CMSSW_7_0_X/devel-gcc48
$ git checkout IB/CMSSW_7_0_X/devel-gcc48
fatal: reference is not a tree: IB/CMSSW_7_0_X/devel-gcc48

It has stopped to work with the last pull request. All the references on Google
talk about submodules, which I don't use. Any ideas what could be causing this
issue?

"Bad" naming. It interprets the branch name as something-gHEX like the
output from git-describe. Coincidently "cc48" is an umambiguous short
sha-1. check_tracking_name, which prefix "origin/" in, never has a
chance to run.

We should probably check in get_describe_name() that the returned
value is a commit or a tag, but that doesn't really solve the problem.
I think check_tracking_name should have higher priority than
get_describe_name()..
-- 
Duy