Submodules are incorrectly reported on some branches

[robnasby]

Scenario:
In a repository, a submodule is added in the DEV branch, but not the PROD branch. In LibGFit2Sharp v0.14.1.0, submodules are reported regardless of which branch is checked out. This is contrary to how Git behaves, which only reports the submodule for DEV.

[dahlbyk]

Repro: https://github.com/dahlbyk/libgit2sharp/compare/gh604

1. Create a repo with a submodule committed in a branch (commit includes .gitmodules change plus new link in tree).
2. Confirm submodule does not exist in master.
3. Checkout branch with submodule, then switch back to master.
4. Submodule now returned with status of Unmodified.

[arrbee]

Hmm. Interesting. The submodules API would probably show the module because it will be present in the repo config, but I would not expect it to show up in the status if everything is clean. I'll look into it - thanks for the detail!

[robnasby]

It seems that the library is using the data in .git/modules, rather than the .gitmodules file. I took a quick look at the LibGit2 library (C is not my langauge of choice), and it indicates in comments that it uses the .gitmodules file. But looking at the LibGit2Sharp code, it seems to delelgate directly to LibGit2. So my guess is that the problem actually lies there.

If someone can confirm this is true, I can open an issue under that project (though I don't have an easy way to confirm it is broken there).

[nulltoken]

@arrbee Is this still an issue in libgit2?

[jamill]

I think you will want to check the status on the submodule via Submodule.RetrieveStatus() to determine where the submodule exists (.gitmodules, , index, head commit, work dir, etc...)

The current API might not be the clearest, but I don't think we want to change this for the stabilization push.

[nulltoken]

There are chances it may be already be fixed. Maybe, some test coverage should however be added.

Labeling it as up-for-grabs and dropping the stabilization label.

[dahlbyk]

Maybe, some test coverage should however be added.

Brought old repro up to date in #1051 - tests pass locally.