Fix 'Tree' object has no attribute '_name' when submodule path is normal path

[CosmosAtlas]

When a repository have a .gitmodules file and the actual path defined in the git repository is not related to submodule, GitPython still assumes its a submodule.

To replicate:

# In a temp directory
mkdir test
cd test
git init
mkdir DbConnector
touch DbConnector/readme.md
touch .gitmodules
# Put the context of the next segment in .gitmodules
git add .
git commit -m "test"

[submodule "DbConnector"]
    path = DbConnector
    url = https://github.com/chaconinc/DbConnector

Then in a python section

from git.repo import Repo
r = Repo('.')
r.submodules

the following error occurs

In [3]: r.submodules
---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
Cell In[3], line 1
----> 1 r.submodules

File ~/.local/share/virtualenvs/GitPython-yvdsleke/lib/python3.11/site-packages/git/repo/base.py:423, in Repo.submodules(self)
    418 @property
    419 def submodules(self) -> "IterableList[Submodule]":
    420     """
    421     :return: git.IterableList(Submodule, ...) of direct submodules
    422         available from the current head"""
--> 423     return Submodule.list_items(self)

File ~/.local/share/virtualenvs/GitPython-yvdsleke/lib/python3.11/site-packages/git/util.py:1184, in IterableObj.list_items(cls, repo, *args, **kwargs)
   1175 """
   1176 Find all items of this type - subclasses can specify args and kwargs differently.
   1177 If no args are given, subclasses are obliged to return all items if no additional
   (...)
   1181
   1182 :return: list(Item,...) list of item instances"""
   1183 out_list: IterableList = IterableList(cls._id_attribute_)
-> 1184 out_list.extend(cls.iter_items(repo, *args, **kwargs))
   1185 return out_list

File ~/.local/share/virtualenvs/GitPython-yvdsleke/lib/python3.11/site-packages/git/objects/submodule/base.py:1406, in Submodule.iter_items(cls, repo, parent_commit, *Args, **kwargs)
   1401         continue
   1402     # END handle keyerror
   1403 # END handle critical error
   1404
   1405 # fill in remaining info - saves time as it doesn't have to be parsed again
-> 1406 sm._name = n
   1407 if pc != repo.commit():
   1408     sm._parent_commit = pc

AttributeError: 'Tree' object has no attribute '_name'

Fixed by adding an additional check when determining whether the object is a submodule. Doing so makes sure only Submodule but not Blob or Tree instances of the IndexObjUnion is considered a submodule.

PS: An example real project with this issue https://github.com/ChaoticOnyx/OnyxForum

[Byron]

Thanks a lot for the fix!

Did you validate this with your particular repository? I am asking as there is no test for this. Thank you.

[CosmosAtlas]

Did you validate this with your particular repository? I am asking as there is no test for this. Thank you.

Yes, I did. With the PR, now r.submodules evaluates to [] as expected in both the test repository and the real-world example.

[Byron]

Alright, I take your word for it.

If you have time, I'd appreciate a testcase in a follow-up PR, but have full understanding if that seems a bit hard to do with this test-setup.

Thanks for contributing.