repo.submodule gives an error in a freshly initialized rep

[mfiers]

It seems that repo.submodule('dir') gives an error (see below) in a repository that is just initialized (i.e. no commits yet).

(some lines omitted)
  File "/home/mf/project/moa/lib/python/moa/template/provider/__init__.py", line 102, in installTemplate
    provider.installTemplate(wd, tName)
  File "/home/mf/project/moa/lib/python/moa/template/provider/gitmodule.py", line 92, in installTemplate
    sm = repo.submodule(thisdir)
  File "/home/mf/local/virtualenvs/moa/local/lib/python2.7/site-packages/git/repo/base.py", line 244, in submodule
    return self.submodules[name]
  File "/home/mf/local/virtualenvs/moa/local/lib/python2.7/site-packages/git/repo/base.py", line 238, in submodules
    return Submodule.list_items(self)
  File "/home/mf/local/virtualenvs/moa/local/lib/python2.7/site-packages/git/util.py", line 659, in list_items
    out_list.extend(cls.iter_items(repo, *args, **kwargs))
  File "/home/mf/local/virtualenvs/moa/local/lib/python2.7/site-packages/git/objects/submodule/base.py", line 883, in iter_items
    pc = repo.commit(parent_commit)         # parent commit instance
  File "/home/mf/local/virtualenvs/moa/local/lib/python2.7/site-packages/git/repo/base.py", line 378, in commit
    return self.rev_parse(str(rev)+"^0")
  File "/home/mf/local/virtualenvs/moa/local/lib/python2.7/site-packages/git/repo/fun.py", line 151, in rev_parse
    obj = name_to_object(repo, rev[:start])
  File "/home/mf/local/virtualenvs/moa/local/lib/python2.7/site-packages/git/repo/fun.py", line 86, in name_to_object
    raise BadObject(name)
gitdb.exc.BadObject: BadObject: 48454144

[Byron]

The bad-object ID is hex for 'HEAD', and it appears that it could not resolve it for some reason. It seems rev_parse() failed and entered a branch where it tries to evaluate the string as object name (SHA), which fails.

Do you have the HEAD reference in your repository ?

[mfiers]

it seems that there is no HEAD (yet) - it might be a git feature/problem (?). If I run:

mkdir test && cd test
git init
git log

I get the following error

fatal: bad default revision 'HEAD'

Which seems pretty much the same.

I only came across this error in testing - I'm not sure this will ever be a real issue.

[Byron]

It would certainly be good to have a check for missing HEADs, however, I don't know how common it is.
Therefore I believe its not a git-python issue.
Thanks for bringing it up anyway, and good luck finding the cause of the issue.

[mfiers]

I agree that it will likely be rather uncommon - I'm catching the specific
error now, which works for me.

Thanks for looking into this.

On Wed, Sep 26, 2012 at 6:16 PM, Sebastian Thiel
notifications@github.comwrote:

It would certainly be good to have a check for missing HEADs, however, I
don't know how common it is.
Therefore I believe its not a git-python issue.
Thanks for bringing it up anyway, and good luck finding the cause of the
issue.

—
Reply to this email directly or view it on GitHubhttps://github.com//issues/73#issuecomment-8879993.

[guysoft]

Hey guys,
I have the problem now,
reproduction code:

#!/usr/bin/python
import tempfile
import git
import os.path

#create workspace
tmpDIR = tempfile.mkdtemp()

tempRepoPath = os.path.join(tmpDIR, "repo")
outRepo = git.Repo.init(tempRepoPath, bare=False)
dest_branch = outRepo.create_head('dest')

Output:

Traceback (most recent call last):
  File "/tmp/code.py", line 11, in <module>
    dest_branch = outRepo.create_head('dest')
  File "/usr/lib/python2.7/dist-packages/git/repo/base.py", line 287, in create_head
    return Head.create(self, path, commit, force, logmsg)
  File "/usr/lib/python2.7/dist-packages/git/refs/symbolic.py", line 505, in create
    return cls._create(repo, path, cls._resolve_ref_on_create, reference, force, logmsg)
  File "/usr/lib/python2.7/dist-packages/git/refs/symbolic.py", line 458, in _create
   target = repo.rev_parse(str(reference))
  File "/usr/lib/python2.7/dist-packages/git/repo/fun.py", line 274, in rev_parse
    obj = name_to_object(repo, rev)
  File "/usr/lib/python2.7/dist-packages/git/repo/fun.py", line 86, in name_to_object
    raise BadObject(name)
gitdb.exc.BadObject: BadObject: 48454144

[Byron]

It would be good to post the stack trace for completeness.
You are welcome to issue a pull request in case you come up with a fix.
Thanks

[guysoft]

Ok, appended a stacktrace to the comment above.
For now I can post that the workaround is to just an empty "init commit".

Like this:
outRepo.index.commit("Init commit")

Not sure if a fix is possible, correct me if its a limitation of git, however perhaps the stacktrace might be able to be more informative. something like "You can't branch from an empty repo"

[Byron]

I will review this one for 0.3.5 - if the git commandline can handle it (and I believe it does), then git-python should do so as well.