Allow submodules to be ignored by reading .gitmodule metadata

[mmjconolly]

Allow a user to specify that a git submodule of a repository should not be considered as input to the dependency resolution algo, by adding a key/val pair to .gitmodules

$ cat workspace/foo/.gitmodules
[submodule "baa"]
    path = baa
    url = https://github.com/baa-corp/baa.git
    wit = ignore

[jackkoenig]

I like the docs and clever idea for ignoring, I didn't even considering trying to add metadata to the .gitmodules file. Do you know for sure that it's safe?

[mmjconolly]

I like the docs and clever idea for ignoring, I didn't even considering trying to add metadata to the .gitmodules file. Do you know for sure that it's safe?

Reasonably confident that it's safe, the .gitmodules file is under the hood a git config format file (ie, section/key/val) that happens to be used for submodules.

I also did some manual tests that preserve/ignore the extra metadata:

• added a new submodule after a previous one already had 'ignore'
• update a submodule that has 'ignore'
• git submodule status
• git submodule foreach

[richardxia]

LGTM, and nice docs!