Fix go mod repo to run only on current git project

[DariaKunoichi]

Use git ls-files to ignore submodules

[TekWizely]

Greetings @DariaKunoichi and thanks for taking the time to make a PR !

so I'm a bit torn, and stuck trying to decide between "only git-tracked files should be considered" and "let's exclude sub-modules"

I'm leaning toward the latter, as it feels more inclusive.

In researching, modern sub-modules keep a .git file (not directory) as a gitlink to the tracked git folder off of the repo root.

Older sub-modules could still contain a .git folder.

My idea is to exclude sub-folders that have their own .git file/folder.

Starting from this SO post:

• Find exclude path containing specific files

I learned about pruning with find and was able to devise this construct:

find . -type d \( -name .git -prune \) -o \( -name vendor -prune \) -o \( -not -path . -exec [ -e '{}/.git' ] \; -prune \) -o \( -exec [ -f '{}/go.mod' ] \; -print \)

This seems to work well in my local, but I'm interested in your thoughts ?

NOTE: Additionally, the cmd-repo-pkg script will need a version of the solution we end up with.

Thanks again, I look forward to further discussion on this matter.

-TW